Vista - vista 64 not stable with games

hi guys just joined the site..been looking through and maybe someone can point me the right way i hope,ok i know very little about pc's thats where my friend steps in,but he does not know vista 64,my rig
vista 64 home premuim,intel(r) core 2 quad cpu q6600 @ 2.40 running direct x10,ram corsair dominator 4x1 gig 1024 running at 1066mhz each,monitor hannspree m19wa 1280x768 60hz,g-card g3force 9600gt 512mb,mb asus p5q-pro,(but i have a spare g-card as well spec geforce 6800 extreme its a fall back card)
NOW FOR MY PROBLEM
games:
TRACKMANIA both tmu and forever,run crap on the 9600gt even with the newest driver,on the bench test fps came back anywhere from 91fps right down to 25fps!! after approx 5 tests then it starts to lock the machine up,have to press ctrl alt delet,then without me doing anything the game takes over and finishes the test,comes up with a low fps,...now if i run it on my low spec card runs 98% better but only at 36.9 fps everytime....
BATTLEFIELD 2 both cards will NOT run this game just flickers and odd looking pic blocks over the top of the screen but you can still see the main pic....
thats the main 2 problems i have but for a one i do the odd beta game test can you tell me what is bitdefender antivirus is it apart on vista ? has this blocks me running some beta games testing online,i can not remember putting this on the pc...HOPE SOMEONE CAN HELP
its the g-cards i need real help with,was starting to think the 9600gt has a memory fault due to the lock ups,all the system is new approx 2 weeks,hope you can understand my problem....i even tried my xp pro 32 bit back on but not much better..

why do you think it's vista , does your system past all the stress testing before you tried games.
-occt 1hr
-prime 3hours
-memtest 1.5 2 hrs
-3d-06
-vantage
-spi-32m
-correct drivers and new vid drivers ,chipset drivers

-that said vista 64 is stable and I know you have a problem but a site like
-http://forums.guru3d.com/ could help better that's a high end gaming hardware site

-what seems odd in your set up is you have your ram overclock to 1066 , but your cpu is at 2.4 stock, if it was me the cpu would be 3.6, ram at 900-1000 where ever is stable and lower timings.
the reason I stated that is that 4x1 sticks will not run on many ,if any very stable @ 1066
-my .02

memory not running at 1066,thats what is wrote on the side of it...

Are these two games the only ones you're having trouble with?

I'd second the suggestion of lowering the RAM speed, although that ASUS board should handle it, I've got 4x2 gig sticks all running at 1066 and it runs just fine.

From what I've been reading of the troubles going on with nVidia cards dying left and right, I'd be suspicious that the card is at fault, even if it's brand spanking new.

never trust your PC to find the drivers automatic !!!!! goto the sites and download them YOURSELF !!! my new pc now runs vista 64 spot on,can not belive it when i run bf2..i did not even know there was stunning flowers in the GRASS spec on the game is set a max on everything and runs 100% great..THANKYOU TO THIS SITE for pointing me the right way... remember guys just read around the forums all the answer's are there..or point you in the right way.also tmu/f runs really good in my eyes 113 fps on setting 1280x768 wide screen