I'm running on high around 30 fps on Crysis.
AMD Athlon 64 3500+, 2.2GHz
1 GB RAM
1 NVidia GeForce 8600 GT (Underpowered, I don't have a 300W power supply :( I can only play on a little lower than medium.)
It used to run around 15 FPS on low with my GeForce 6800 XT. Once I get a new power supply, I'm thinking of maybe getting another 8600 GT and SLIing them.