Aero Glass is deactivated while the tests are running so that it will not confound the measurements. While running, the tests show only a progress bar and a 'working' background animation. The current version of Windows Vista (Build 6001) version of WinSAT performs the following tests: The WEI is also available to applications through an API, so they can configure themselves as a function of hardware performance, taking advantage of its capabilities without becoming unacceptably slow. However, few software or hardware vendors have done so to date. Microsoft also intends that hardware manufacturers publish the WEI scores of their computers. Microsoft intends that software publishers list WEI scores to specify hardware requirements instead of specific technical parameters (such as '256MB of RAM or more'). For example a computer with the lowest subscore being its memory, would benefit more from a RAM increase than adding a faster hard drive (or any other component).

The WEI can also be used to show which part of a system will provide the greatest increase in performance when upgraded. For example, the Aero graphical user interface recommends a WEI score of 3 or higher for satisfactory use of the 'Aero Glass' feature. The WEI allows users to match their computer hardware performance with the performance requirements of software. The WEI includes five subscores: processor, memory, 2D graphics, 3D graphics, and disk the basescore is equal to the lowest of the subscores. The WEI is due to increase its maximum score with future updates. The Windows System Assessment Tool ( WinSAT) is a module of Microsoft Windows Vista which measures various performance characteristics and capabilities of the hardware it is running on and reports them as a Windows Experience Index (WEI) score, a number between 1.0 and 5.9.

Windows system assessment tool