The graphics card must fully support Direct3D v9 or above. This implies that the graphics card driver must support DDI version 7 or above. This can be determined by going to Start->Run and typing in dxdiag. Click on the Display Tab and the DDI version is given in the Drivers Box at the top right.

The card will also ideally need at least 8Mb of RAM. However, it may be possible to get some 4Mb cards working at lower screen resolutions.

In reality any fairly modern graphics card from the last 2 or 3 years should work OK. All of the current ATI or NVidia cards are fine.

Let me know if you need any further info.

Mark