You didn't say 32 or 64-bit Win7. That makes a difference. You also failed to mention that system shipped with XP Media Center, not Win7.

Did you download the drivers from AMD/ATI directly? According to their site, Win7 is not officially supported on the Xpress 200, but you can try the Vista drivers.

http://support.amd.com/us/gpudownloa...2&lang=English
Note: AMD’s DirectX 9 ATI Radeon graphics accelerators are not officially supported under Windows 7. If the user chooses to, they can install the ATI Catalyst Windows Vista graphics driver under Windows 7. Please be aware that none of the new Windows 7 graphics driver (WDDM 1.1) features are supported (as the Windows Vista level graphics driver is limited to WDDM 1.0 level support). Using the ATI Catalyst Windows Vista driver under Windows 7 is not officially supported by AMD, and as such AMD will not provide any form of customer support for users running in this configuration