Sanad

My specs are:
E6600 @ 3.4ghz
8 GB GSkill DDR2 1000mhz
500GB x 3 RAID0
NVIDIA 8800GTX
Win Vista Ultimate 64bit

Problem is games arent running on my PC. I installed crysis and cod4 and as soon as i click on em, window comes up saying Crysis stopped working and starts collecting information. I just built this computer. I also installed Pro Evolution Soccer 2008 which worked fine at first. The next time i started it, it says that the graphics dont meet the minimum requirements! Gears of War is the only game that works fine and i'm about to end it so i need to figure the problems out! I have installed only the four must-have updates of vista which were also mentioned in the forum as well as on extremetech. I dont have internet on vista pc cuz my isp's modem isnt compatible with 64bit so im downloadin stuff on my xp laptop. Please help me! I dont wanna switch to XP!!! I also video edit hence the ram so i cant go to 32 bit either! If there are any updates i should install please provide me with the link! Thanks.