full screen not working in windows vista home premium

i have a brand new awesome computer that i saved up the money for years and now that it's built windows won't run fullscreen games without crashing and blue screen of death, it will run cube sauerbraten full screen 200fps. also i have used a performance program to test the speeds and it runs at 400 fps when not in full screen and in full screen it runs at below 50,

my setup
asus m3a79-t
amd phenom x4 9950 oc'd to 2.9 in bios
2 ati radeon 4870 x2's
16g ram
1200 watt psu


i also have reinstalled vista 3 times now and it still doesn't work. along with only install the newest drivers on installation, all fresh downloads. so i'm very sure it's vista and not my drivers. but it does keep saying that they have crashed.

Hi 1dude1,

My name is Lindsey and I work with the Windows Outreach at Microsoft. I saw you keep seeing the blue screen of death when you try to play games on your new computer. I am sorry this keeps happening. I am not a tech support but maybe some of my hints can help you. Have you made sure you have all of the updates in Vista? Sometimes even new computers need updates. Here is a link so you can learn more about the Service Pack 1 and other updates; http://www.microsoft.com/windows/w [...] /sp1.aspx. Also you should check out the Windows Vista Compatibility Center to make sure your games and everything is compatible with Vista. I am sure you won't have a problem but this is a great site to have on hand: http://www.microsoft.com/windows/compatibility/. I hope this helps!

Thanks
Lindsey

it sais that sp1 is installed but i am still having the exact same problems. also i never got a long installation, the 30 min one i was expecting. so i don't know if it's fully installed