I'm playing @ Ultra settings on my desktop (Core i7 950, 12GB, GeForce GTX285) with no problems.
I had to run the game on low settings on my laptop (Dell XPS M1530 w/C2D T7600, 4GB, GeForce M8600GT), though. Too jerky at the built-in medium settings, but I may tweak it a bit to see if I can...