Windows Experience Index
While you have the Windows 7 System window open, you may also want to take note of some other basic information about your computer.
The subheading directly below Windows edition, System, displays some Windows 7 hardware information about your computer. The first listing, Rating, displays the Windows Experience Index for your PC. This number is an overall rating that Microsoft uses to determine your PC hardware performance. You can click the Windows Experience Index link to get detailed info about your PC.
As you can see from the above screenshot, the overall rating that Windows Experience Index gives your computer is determined by the lowest rated Subscore. For example, you could have the best processor, 16GB of RAM, a 10,000 RPM hard drive, and still have a Windows Experience Index of 3, if you don't have a premium graphics card. A low Windows Experience Index rating does not necessarily mean that you have a slow computer. However, if all Subscores are 1-2 or lower, you may want to consider upgrading to a faster PC.