PC Freezes.. Videocard?

Hello!

The last few days im having troubles with my computer the problem is: When i play some games (Crysis:Warhead/Call of Duty 5/RainbowSix vegas2) my computer hangs after a little playtime (5/10mins with cod5/crysis) Rainbowsix instead can be played whole day and gets only a freeze of 20sec.. after the freeze (if i can alt-tab atleast) i got strange "artifacts?" and another alt-tab fixes this and i can go on..

With rainbowsix its no problem cause i get it not that much but with crysis/cod5 this happens every 5/10mins and its really annoying..

My setup: (nothing is OC'ed)
Mobo: P5K PRO
CPU: E8400 with an Zalmancooler
Vidcard: 8800GT xxx Alpha Dog
Ram: 4GB Kingston 800
OS: Windows XP 64bit
PSU: 660watt (dont remember name)
Soundcard: Soundblaster Xtreme Music

Things i've tried to solve it:
Reinstalled windows with newest drivers.
Reinstalled windows with Forceware 169.?? video drivers (tried this driver since i had no problems a halfyear ago with just Crysis)
Did a artifact test with ATItool no problems found. (maybe i should do it again)
I've took my videocard into my brothers computer and he had NO problems at all i could play crysis 1h and nothing happend while in my computer it would freeze 20times already o_O?

I cannot run memtest yet cause im out of CD's (what a shame)

I thought it was overheat but at my bro's pc my videocard gets allot warmer around 90C while mine is at 80/85.. (checked this with speedfan)

some images what happens to my screen
http://img256.imageshack.us/img256/7526/crysisc.jpg
http://img5.imageshack.us/img5/6268/crysis2s.jpg
http://img7.imageshack.us/img7/8355/crysiswtf.jpg

http://www.youtube.com/watch?v=KLDzEsFB23U (as you can hear my sound doesnt hang.. after pressing the windows button a few times it goes to windows sometimes......)
http://www.youtube.com/watch?v=qOz-kphL3Lo
yes im bored while recording :>


Another note: Im not having any problems in windows or programs like photoshop.. its stable like any other pc.. World of Warcraft doesnt got any freezes and same counts for Call of Duty 4. those 2 games are stable and got never probs with it.

Hope you guys or maybe even girls can help me out Sorry for my english

even if another pc can cope with 90 doesnt mean urs can. whats the temp running WOW and COD4?

Thanks for the replies. i did some tests and it seems it really is a heat problem (strange since i could run the first crysis and had no problems).. My card is getting pretty warm in there something like 90/95c in crysis and in WoW its around 75C.

i've clocked my videocard to an standard 8800GT and i think its better now.. Since i've the alpha dog xxx version which is 670Mhz if im correct.. and the standard one is 600. Also i've put the fan speed on 100% and could run crysis maybe 45mins without problems :> gonna play it for a few times to see if its really the heat