So, you're going to buy a computer and it comes with Windows Vista.  The computer has 512MB of memory, a dual core processor and an 80 gigabyte hard drive - best of all it's really cheap!  Sound good?  Well, maybe not.

These days you see more and more computers for sale with the Microsoft Windows Vista operating system.  As an eBay seller, I sell a number of computers with Vista installed.  You'll notice that I don't sell computers with 512 megabytes of memory and 80 gigabyte hard drives with Vista - this guide explains why.

There are a few things you need to be aware of when buying a computer that runs Vista in terms of the hardware.  Here's my list in order of importance.

1. You need at least 2 gigabytes (GB) of memory.  Windows Vista requires more memory than Windows ME, 2000 or XP.  The computer I'm using right now to write this article is running my IE browser, Microsoft Outlook and Excel.  My current memory usage is 1.2 gigabytes!  Keep in mind though I am running the Aero interface, but that's another item in my list.  I strongly suggest that any computer running Vista have a minimum of 2 GB or memory, otherwise your computer could run out of physical memory and start using the hard disk which will slow things down dramatically.
2. If you want to run Aero, then you need and adequate video card.  Aero is the new "fancy" desktop that features translucent edges on the windows, three dimensional effects among other features.  This is a really video intensive feature.  If you are buying a desktop, then make sure it has a good quality video card, preferably with at least 256mb of memory.  If you are buying a notebook, then you will need a discrete video card to handle Aero.  What a is discrete video?  It means that the notebook uses a separate video card with its own dedicated memory so it doesn't share the main system memory.  Many Dell notebooks come with Intel integrated video as standard, then either nVidia GeForce or ATI Radeon graphics as an upgrade.  So, while the integrated graphics will be okay for the standard Windows desktop, you'll need a discrete card for Aero.
3. Don't skimp on the hard drive.  The Vista operating system can easily take up 8 gigabytes or more.  If you add newer software packages like Office 2007, then that can quickly balloon up to 20 or 30 GB.  An 80GB drive should be an absolute minimum.    Also make sure that the hard drive is a SATA II drive, these are the newer generation of mass market drives and can access your data significantly faster than the older IDE models.
4. The processor is important too, but not as critical as the above.  Some people won't agree with me on this, but I don't think that paying a large premium for the latest fastest processor is really worth the money.  Any of the new dual core processors will provide enough horsepower to run Vista comfortably.  Processor speed is more dependent on the applications you will run.  That said, if you want to edit videos, are a developer running C++ compiles, or play any of the newer games, then processor speed starts to become and important factor.  If you are planning to do more basic tasks then you are better off making sure you get the memory, hard drive space and video performance addressed first. 

Keep in mind that you don't necessarily have to buy a computer with all of the memory you need, powerful video card, etc.  Any desktop or notebook computer can be upgraded as far as memory is concerned either by adding more memory or replacing the memory you already have.  Desktop computers all come with a video card slot that allows you to upgrade to a more powerful video card with more memory, however with a notebook this is not the case.  Hard drives are easily upgradable in either desktops or notebooks - if you can't do it yourself, any competent tech can do it for you.

Your last option is to get that cheaper computer and buy a copy of Windows XP and install that instead.  It's reliable and doesn't have the hefty hardware requirements that Vista has.