Actually the HardOCP demos are very badly CPU limited, at least for the X800 XTPE. You can see it from the graphs; XTPE scores basically the same scores for all AA/AF settings. The 6800U and 6800GT drop with increasing AA, and X800 Pro drops also, but interestingly not as much.
Anyway, the HardOCP bench doesn't tell anything useful, except that all the top notch cards can play the game easily at 1600x1200 4xAA 4xAF. We would need something like 2048x1536 4xAA 4xAF to hurt these cards in these timedemos, lol.