Nvidia has a new driver out that supports the 8800 GTS 512 GPU and it is the new recommended driver for the latest DirectX 9, 10 and OpenGL.
It is out for XP 32 and 64 bit, Vista 64 and 32 and it is the new driver recommended for Crysis. A few people on some forums have tested it in Crysis, and they were disappointed to learn that there were no significant frame rate improvements.
It also includes numerous game and application compatibility fixes and you had better get it. Beware, however, as it is not WHQL certified.
You can get it here.