When buying a laptop be very scrupulous in your choice.

Consider these factors: What am I currently going to be using the laptop for?

                                    What may I use it for in the future?

                                    Who else in my household may be using it and what may they use it for?

After thinking of an answer for those questions remember that there is only one part of a laptop that is typically easily upgradeable and that is the RAM. It is often wise to spend a little more in the beginning for something that will last you.

If you think in the future you might like to do some advanced video editing, gaming, CAD or something similar get a computer with a dedicated graphics card. A laptop with an intel graphics card is certainly not going to be dedicated but be careful because Nvidia and ATI both offer integrated graphics chips as well.

If you think in the future you would like to do some photography make sure you have a card reader because this simple feature will save you time and money. Time because transfer rates between a card and a reader are faster than a camera, a card, a usb cable, and a laptop or desktop. Money because you don't have to spend $20 or so later on.

If you travel a lot make sure and get something with a strong case. A strong casing would be magnesium alloy like a lenovo/ibm thinkpad uses or carbon fiber like Sony uses on their higher end business class laptops.  Definitely keep battery life in your mind as well, the only thing you can do to increase this is to turn everything to it's lowest output potential or buy an extended life battery. Most of the time the higher end your processor is the more efficient it is therefore an AMD TL-62 or higher; or Core 2 Duo T7100 or better is something to consider if you want battery life over 3hrs.

For anyone buying a computer it is a good idea to fork out a little more money on what I deem as necessary accessories.
These Accessories include but are not limited to: An external hard drive, battery backup, and a good sturdy laptop bag.

Purchasing an external hard drive whether or not your buying a laptop or desktop or you already have one is one of the smartest things you can do. Buying a Seagate, Western digital, Samsung Pleomaxx or any other high quality external will make your life less stressful because a computer can and probably will crash on you at the worst possible time. Having that external means that you don't lose all your pictures, music, documents, financial files and so on that you spent so much time trying to get right and get onto your computer when something bad does happen. In the event your computer does crash just find a friend with a laptop or desktop or if you have another computer and transfer what you need onto their/that computer and at least you have a shot at completing what you originally set out to do.

Having a battery backup on a laptop if it is a desktop replacement or a desktop is also something that will save you money in the long run. In the typical American home we have tons of a devices on our 110v outlets some of which that are considered high drain appliances.  If you have a dryer, fridge, window A/C(s), or anything similar that you notice slightly dims your lights this device could damage your computer with an under-voltage and a regular surge protector does very little if anything at all for an under-voltage unfortunately; in this case it is a smart idea to get a battery backup. A battery backup is also a good idea to protect your sensitive electronics (Laptop, desktop, router, cable modem, game console, etc.) from the weather because they also work as great surge protectors and give you a few moments to shut things down properly in the event the power goes out.

Before buying a laptop or desktop consider everything you might have to purchase in order to keep that thing running properly, to suit your needs and as well as to keep it working for a long time.