Since the GeForce 7900 GT lacks support for HDR+AA, we’re running that card with 0xAA/16xAF. To keep frame rates high, we also decided to disable AA for the Radeon X1950 Pro. The GeForce 8800 GTX and Radeon HD 2900 XT are both running with 4xAA/16xAF.
Performance is generally pretty comparable for the GeForce 8800 GTX regardless of OS used. We saw a slight, 2% advantage for the GeForce 8800 GTX SLI setup at 1600x1200 but honestly considering we’re running FRAPS to test performance with this game this could fall within margin of error. Interestingly enough, the Radeon HD 2900 XT ran about 10% faster under XP than Vista.