I just picked up a 320MB 8800GTS myself and I am VERY pleased with it.
Lost Planet with almost everything on high at 1280x720 under Vista is a very nice thing. That's with 1.5gigs of memory and a 3800+ X2 socket 939.
Also, with a 6600C2D, 2 gigs of some good memory, and a good P35 mobo, you should be good to go for Crysis on high settings.