WEI breaks down the graphical capabilities of your system into two separate sub-scores. This first sub-score (Graphics) is for desktop performance, specifically that of the Windows Aero user experience. The second graphics-based subscore (Gaming graphics) is for 3D business and gaming graphics performance.
Microsoft provides the following information about interpreting a base score:
1.0 to 1.9 - Basic performance. Even a component with a 1.0 subscore meets the Windows 7 minimum requirements.
2.0 to 2.9 - Enhanced performance. Windows Aero may be available.
3.0 to 3.9 - Windows Aero will be enabled.
4.0 to 4.9 - Good performance with high-resolution displays and multiple displays.
5.0 to 5.9 - Capable of running high-end video games, 3D modeling applications, and high-end video editing applications.
6.0 to 6.9 - Supports DirectX 10 graphics with high frame rates at high resolutions.
7.0 to 7.9 - Highest performance level available. Reserved for systems with SSD hard drive, high-end graphics card, and multi-core (i.e. 8 or more) processor.
However, WEI should not be used as a benchmarking tool because of many severe limitations. See this thread.
Windows Exerience Index True?