Just flashed my EVGA 8800GT SC card with the 8800 GT Mac BIOS and it works great in OS X and Vista 64. Apple wants $399 and I only paid $200!
Mac 8800GT BIOS: http://forums.macrumors.com/showthread.php?t=434092
Mac 8800GT BIOS: http://forums.macrumors.com/showthread.php?t=434092