This text is offered exclusively as an eBay guide for those who may find it useful.

Introduction

The purpose of this guide isn't to make you a computer expert, or to fill you in on all the latest technological advances hitting the PC market, but rather to try to offer you a starting place to make more informed computer purchasing decisions in the modern computing world, and to make you better prepared to find a computer that's well-suited to your needs. If you're looking for a thorough analysis of all the individual components of the modern motherboard, then this isn't for you. If a short and simple introduction is more up your ally, then please read on!

Speed

There are a variety of different parts of the basic computer which come together to determine how "fast" it is. Almost every part of your computer that serves a purpose takes a certain amount of time to do its job. For example, if you are looking for a computer that will be able to quickly render the newest 3D games, the computer's graphical processing unit (GPU) - or more reasonably, the amount of video memory - is going to be what you want to look at. (Don't go running off just yet, we'll get to all of that.)

The vast majority of the time, however, when you hear someone talking about how fast their computer is, they will be referring to the computers processing speed. That sounds a little scary, but it really shouldn't be - all we need to know about that for our purposes is that the processing speed is essentially how fast the computer can "think", in its own special way.

Now, since speed is such a very important factor for most consumers, the processing speed will almost always be clearly advertised, or the name of the processor (the part of the computer that handles all of the "thinking") will be given. If the speed is provided, it will either look something like "4.2GHz" or appear as something along the lines of "AMD [model name] 4200+", where "4200+" is the indication of how fast the processor should be. Unlike most other guides out there, I'm not going to give you a lengthy breakdown on what all of these numbers mean, but I will try to give you some idea of how to use them to influence your decisions.

Firstly, as I've said, some computers will not have their processing speed clearly advertised. If this is the case, save yourself a headache and ask the seller. Once you know the speed, the chart below should provide you some idea of what it means, as of the time of this writing (November, 2006). Another thing to note when looking at a processor's speed is that newer processors are "dual core". For the sake of simplicity, simply multiply the given speed of "dual core" processors by two for use in the chart below.

Processors featuring speeds of 4200+ to 5000+ or 4.2GHz to 5GHz (and above) are typically on the higher end of the processors offered today. These processors should be adequate for even the most intensive uses for a couple of years to come, and for the average users, processors featuring these speeds will be able to run non-demanding applications, such as Microsoft Word for the entire life of the computer. Another thing to note about these processors is that as they're the current top-of-the-line and computers featuring these units will also feature the greatest amount of price inflation, so (as always) be sure to shop around to make sure you're getting the absolute best deal, and constantly evaluate what your actual needs are before making your purchase.

3000+ to 4200+ or 3GHz to 4.2GHz is the typical range for the middle-line computer models available today. Computers featuring these processor speeds should be able to run all modern, high-end applications with a fair amount of ease, and will run your everday applications, such as Microsoft Outlook, etc. well into the future, but may not be able to run the very demanding applications that will be introduced in a few years time.

1.4GHz to 3000+ or 3GHz is considered to be on the lower end of the computers that are available in stores today, but don't let that deceive you! These computers are still very capable of running most basic applications, and would make excellent school or office computers for those who don't have need to run powerful applications.

Anything below 1.4GHz would be hard to come across in stores now-a-days, and these systems will most likely not be suitable (or compatible) with the the new Windows Vista operating system which is due to hit store shelves soon. For those who are comfortable with running older software, however, and simply need a computer to browse the web or run basic applications, anything above ~800MHz will still do the job reasonably well. But if you're looking to get a good investment value, you'll want to stay away from these systems, unless you find a deal that is just too good to pass up. (For example, I recently purchased a used computer system with a 900MHz processor for $35. It's currently running Windows XP and still makes an excellent web browsing and word processing computer.)

Memory

The amount of memory your new system has should be your next greatest concern. Put simply, if a computer has less memory, it may not run as effeciently as it could, or may not be able to multi-task (handle multiple things at once) as well as a computer with more memory. Computer memory also has a certain speed at which it operates, which will play a part in how fast your computer can process information overall, HOWEVER, in general, computer manufacturers are good about including memory that has a speed suitable for the system it's included in. While sometimes manufacturers do try to cut corners by throwing in slower memory, we will save some headaches by assuming that the manufacturer of our new computer system, like most, elects to keep the memory performance on par with the value of the system, and save ourselves that particular headache.

So, the only thing that we should really want to know is how much memory the computer we're looking at has, and whether or not that will be enough for our uses. Let's take a look at Windows XP, which is the current mainstream operating system, which most computers will include some derivative of. The minimum memory requirements for Windows XP, as stated by Microsoft (caveat emptor), is 64MB. Therein lies a lesson: keep an air of caution when viewing the minimum requirements stated by software vendors - these measurements are often set at the absolute poorest level of performance so as to increase potential sales, at your expense.

A better estimate for a Windows XP system's minimum memory requirements would be 256MB. This will work, but if you hope to run multiple or demanding applications on your computer, and want the most out of your investment, look for a minimum of 512MB. If, however, you're looking for a computer with the best upgrade potential (such as to Windows Vista) or for a computer to run the latest games, your minimum memory requirement should be 1GB. (And if you're the kind of person who likes to leave programs open, or forgets about them - like me - just remember, all of those open programs take up memory, so it's better to have more of it than less.)

One last thing to note, as memory is so very key to the purchasing decision, it should always be clearly advertised. If it is not, be sure to ask before making a purchasing decision, and if you're ever caught in a bind for determining how much memory you'll need, it's probably better to overestimate than to purchase a system which will ultimately fail to meet your needs.

Storage Space / Hard Drive Size

I'm going to keep this one simple. Very few modern computers on store shelves today will have a storage capacity of less than 80GB, and for the average person, that's more than enough, but to get a better understanding of what storage space means, it's helpful to keep a couple of things in mind.

First, you might want to know that a gigabyte (GB) is the same as approx. 1,000 megabytes (MB), so a computer with an 80GB hard drive will have approx. 80,000MB of storage space (This is not an accurate measurement, but it's close enough for our purposes). Now, let's consider how much media that can hold (since that's what most of us really care about).

Firstly, the average MP3 (song file) is going to be around 4 or 4.5MB. It's significantly more difficult to determine the size of the average movie, due to a variety of factors such as video size, run-time, and quality, but let us assume that the average DVD-quality movie will take about 1,500MB of space, and the average modern, intensive games will take about the same.

Using only 40GB (half the space) of the hypothetical 80GB hard drive, we can store about 10 modern games, 10 full-length movies, and 2,350 songs, and still have plenty of free space left over. What should this mean in terms of your purchasing decisions? With so many manufacturers boasting 300GB+ hard drives, just remember that (with very few exceptions) you'll probably never use anything near that, so unless you're a real media-holic, don't let the storage capacity of your new computer be a very large factor. All modern computers should have more than enough for your needs.

(One last, minor note on hard drives: Like all other functioning components of a computer, hard drives have a certain speed at which they can "fetch" data. For the absolute best performance, look for hard drives that offer higher RPM's (revolutions per minute). Typically, however, modern desktop computers should be equipped with 7,200RPM hard drives, while laptops will have 4,200-5,400RPM hard drives.)

Video Memory / Graphics Cards

Next in line, we'll take a look at the video memory of your new computer. First off, if you don't intend to ever play the latest games on your PC, watch movies or capture video with extremely high clarity, or work in 3D modelling applications, the video memory shouldn't even be a factor in your purchase. If, however, you meet any of the aforementioned criteria, you will want to know the video capacity of the system you're looking at.

NOTE: The text below goes into significantly more technical detail than you may be used to at this point. If at some point you think it's too much to bear, to determine if your computer will be able to run the latest game, etc., you can always ask your friendly salesperson, who should be able to provide an honest and accurate response, but for general purposes, don't expect a computer with less than 128MB of video memory to play the latest games, and don't expect a computer with 256MB or more of video memory to be cheap, as increased gaming capacity will almost always artificially inflate a computers value.

Now, with that aside, when we're looking at a computer system's video capacity, you will want to know right-off-the-bat what the amount of video memory that system has. Generally, 64MB will be adequate for a good movie-watching experience and for playing older or web-based games, but will not be able to power more modern or graphics-intensive games. 128MB will power most modern games, but may lack some of the extra features that the latest releases utilize, such as more advanced shadowing or rendering capabilities. 256MB and 512MB of video storage should indicate that the card will be capable of handling all modern games, and have a very good chance at handling the new games that are available around the corner.

Still, it is important to note that due to the ever-changing nature of the PC game market, and the amount of strain that modern games and 3D applications put on computers, always check the system requirements listed on the game or software application you are thinking of purchasing, and base your decisions from there.

It is also very important to know about what kind of video device your computer has. (At this point, if it's not mentioned, ask the seller if the computer uses onboard video. If it does, ask if the onboard video uses shared memory or not, and read on. If not, skip to the next paragraph.) Onboard video is generally going to offer poorer performance vs. a system that has an equivelant, dedicated graphics card. Worse still, in the realm of onboard video, there's a little something called shared video memory. What this means is that the video processor will take memory away from your computer's RAM (the main memory we talked about earlier) in order to work with video data. So, unless your computer is equipped with a lot of spare RAM, try to stay away from shared video memory.

As I said, a dedicated video card will typically improve performance over standard, onboard video. However, depending upon the interface of the graphics card, you will also notice certain speed advantages or disadvantages. For that reason, if it is not advertised, ask the seller what interface the computer's graphics card uses. Depending upon what the seller says, just know that generally a PCI graphics card will offer slower performance than an AGP graphics card, and an AGP graphics card will offer slower performance than more modern interfaces, such as PCI-Express.

At this point, I've bypassed a lot of the fine details of the video and graphics side of computing, and that's simply because there are so many possible features that any given video card could have that another won't, and too swift an amount of change in the world of gaming and 3D development. For that reason, if you should find yourself seeking more information about how computer video works, I'd highly recommend you do the following: Take a trip over to google, enter the search string "how graphics cards work" and click I'm Feeling Lucky to be taken to the related howstuffworks articles, which does a rather wonderful job at expelling that information.

Also, you may want to browse the websites of the leading graphics hardware providers at nvidia.com (NVIDIA) and ati.com (ATI Technologies, a division of AMD).

Sound

If you like to listen to music on your computer, as most of us do, you'll want a computer that--literally--sounds good. For these purposes, there are two things I would recommend. First: Listen! Listen to something on the computer (preferrably a song or a movie) that you're thinking about purchasing; this is the best way to gauge whether or not you like how it sounds. Do note, however, that this may not be entirely accurate depending upon the speakers that are being used and other factors, or may not be feasible due to shopping online, etc.

So, for those reason, you may want to take the time to find out about the audio hardware included with the computer. For most computers, all audio is going to be processed on the motherboard, which is generally, but not necessarily worse than the computer having a stand-alone sound card. (You can consult the salesperson to discover this, but if it is not expressly stated that the computer comes with a sound card, you can assume the computer has onboard audio).

That being said, all that's left to do is to look at the features offered by the onboard audio or dedicated sound card. The information that should be given to you is the number of audio channels supported (The more channels, the better the surround sound experience is generally going to be, if you have an appropriate sound system.) and any additional features of the audio controller that may make your listening experience more enjoyable, such as immitated surround sound for laptops.

With that behind us, it is worth pointing out that most consumers will never have a problem with the way their new computer sounds, and if they do, it is more likely due to the speakers they use, as opposed to the computer's sound hardware, so unless you're a real audiophile, you won't have to worry about your computers sound - Just make sure you get a decent pair of speakers, and you should be good to go.

More to Come

At this point, you will notice that I've left a lot of stuff out. (Such as the delicacies of shopping for laptops, choosing the right monitor, where to buy, etc.) My goal was simply to give you a brief introduction as far as what to look for in a modern computer. It might be worthwhile to check back at a later date, however, as I may be adding additional information to this guide, from time-to-time.

Until then, good luck shopping!

- This text is offered exclusively as an eBay guide by the sole author, whose credentials include being a CompTIA certified computer/network technician and internetwork professional, a U.S. subject matter expert (SME) on Internet technologies, certified Microsoft Office Specialist and computer generalist, and one of the world's last friendly tech-guys. :) -