Ok, finished a quick runthrough of benchmarks. I have an ATI 4850x2, and a core 2 at 3.2Ghz.
Crysis had lower framerates, but out of the normal games I play, it was the only one. CoD4 stayed the same, nothing noticeable. But with Farcry 2, World in Conflict, and neverwinter nights 2, I noticed a performance increase anywhere between 5 and 15 percent.
Granted, I did this pretty quick, and only one runthrough of each game, so there should be some differences if I did things a little more complete. I might download lost planet here in an hour or two.