“The new graphics capabilities in Windows Vista will require a powerful graphics engine if you want to take full advantage of all the new and cool stuff, such as the new Aero Glass look. You probably want to avoid the low-end of the current GPU range and make sure you get a GPU that supports DirectX 9 and has at least 64MB of graphics memory,” a special article by Microsoft dedicated to hardware requirements of Windows Vista explains.Microsoft explains on its website a DirectX 9.0 compatible card with 64MB memory is an entry-level recommendation. Higher-end graphics cards will be preferable to run Vista's advanced interfaces such as Areo Glass, Aero Express and Diamond. However, Vista will also contain a light version of its interface to support notebooks which tend to have less high-end graphics.
Other hardware recommendations from Microsoft to provide an adequate user experience include a 64-bit CPU from AMD or Intel, 1GB of memory, a 7200RPM Serial ATA HDD with 8MB cache and NCQ (Native Command Queuing), DVD±RW optical drive. For rapid networking technologies Microsoft recommends 54Mbps or 100Mbps to be supported by the PC. Read more at X-bit Labs