Windows Vista delivers a major step forward in terms of how graphics hardware
is used by mainstream Windows-based applications, from the Windows desktop to
consumer and line-of-business applications.
To achieve this enhanced desktop experience, the graphics adapter or chipset
must have a Windows Vista Display Driver Model (WDDM) driver and must support
GPU, memory, bandwidth, and other requirements supporting Aero capabilities.
For Windows Vista, graphics requirements for desktop experiences are defined
in relation to differentiated experiences, as described in the Windows Vista
Logo Program requirements and the Windows Driver Kit (WDK).
source :
http://www.microsoft.com/whdc/device/display/aero/default.mspx