I just finished the demo. I ran it on Vista with settings at max, 1600x1200 resolution. No lag at all. I'm on a 8800gtx 768 meg card though, and have 2 gigs of system memory (dual 6700 cpu). Runs great. On Vista, it looked perty. Dunno how much of that was Vista though. I may load it on XP to see the differences.
Didn't care much for the "rails" feeling though, either. There were a few place I felt I should have been able to get to, but was blocked via an invisible wall, or convenient debris. But still looks like a lot of fun nonetheless. I shall buy it tomorrow.
Edit: Oh yeah, I forgot. I'm on some old drivers. 7.15.00.5824 looks like (April 2007).
This comment was edited on Aug 21, 00:21.