I've recently upgraded my graphic card from Nvidia 8800GT to ATI 4870x2 and tested it with crysis warhead. I keyed in the playable settings I previously used for my 8800GT ,but it's not smooth.
Note: game tested using windows xp
(Very High, 1440x900, AAx2 - not smooth)
My computer specs
Intel Core 2 Duo E6750@ 266Ghz
Gigabyte EP35-DS3 motherboard
Sapphire ATI 4870x2@ 2GB VRAM
Vista Ultimate 32-bit/Windows XP Professional 32-bit (Dual-Boot)