When you buy software, there’s always a list of computer requirements on the side. It looks something like this (taken from World of Warcraft):

• 800 MHz or higher CPU.
• 256 MB or more of RAM.
• 32 MB 3D graphics card with hardware Transform and Lighting, such as GeForce 2 or better.
• 4 GB or more of available hard drive space.
• DirectX® 9.0c or above.
• A 56k or higher modem with an Internet connection.

That’s pretty hard to understand if you’re not a computer guy. Windows Experience Index (WEI) gives you a single number, and a set of numbers, that summarize your computer’s capabilities. So, if I want to buy a game for my Dell Latitude D820 with a WEI of 3.1, I just have to make sure that the game’s minimum WEI is 3.1 or lower. Software can also be more specific, and list a Graphics or Gaming Graphics requirement. As you can see from my score, my graphics are the weak link in my computer. (info on interpreting and improving WEI after the jump)

When you install Windows Vista, it calculates a WEI for you. The WEI base score (3.1 in my case) is the LOWEST of your five WEI subscores. That makes sense, because it’s your slowest component that bottlenecks your computer’s performance. To view your WEI, follow these steps:

1. Click Start, right-click Computer, and then click Properties.

2. In the System window, click Windows Experience Index.

If you have a score of 2 or higher, you’re fine for browsing the Web, reading e-mail, and using Office apps. If you have a WEI lower than 3, you can’t run the translucent, 3d Aero interface. A base score of 4 or higher means you can run all the new Windows Vista features without slowing down, including recording and playing back HDTV. A base score of 5 is the fastest computer available at the time Windows Vista was released, but we’ll certainly see faster computers soon.
To improve your WEI, start by updating as many of your drivers as possible. The easiest way to do this is to run Windows Update by clicking Start, typing Update, and then clicking Windows Update. Then, click Check for updates, and install any available hardware updates.

If that doesn’t solve your problems, check your computer manufacturer’s website for updated drivers. Last, check your video adapter manufacturer’s website for new drivers. New drivers can only improve your performance a little, though. If your hardware isn’t fast enough, it might be time to upgrade the component with the lowest WEI score. Check this page (which I wrote for Windows XP) for general information on how to upgrade hardware. If your computer is more than a couple of years old, it might be time to buy a whole new computer.

After you update a driver or upgrade your hardware, open the WEI score window again, and then click Update my score near the bottom-right corner of the window. Windows Vista will re-test your computer and give you a new score.