Crysis @ 1280x1024 4X AA, Maxed out (yes sorry my old monitor broke, so I have to use this 1 till I buy another):
5870 @ 850 mhz ( avg Framerate: 41 min Framerate: 35)
285 GTX @ 700 mhz (avg Framerate: 34 min Framerate: 21)
285 GTX sli @ 700 mhz (avg Framerate: 54 min Framerate: 24)
285 GTX tri sli @ 700 mhz (avg Framerae: 63 min Framerate: 18)
Alright? For a game that is an Nvidia came, the min frame rates suck!
Although the avg gameplay is high on the sli and tri sli, the min framerate ruins the pace of the game. I would end up at a wide opening and the Nvidia's would struggle to maintain even 30 fps, in a scene with no action, while the 5870 would stay at a stable 42 (Yes 42 fps, weird number, but its always at that!)
The same rules apply with Crysis Warhead as above.
I'm going to benchmark more now and see what I can come up with, I seriously wouldn't play Crysis just because the min frame rates would just ruin the game. Although i did beat it on my laptop with the settings on high/medium, but atleast I could justify a laptop!