100% run speedfan and realtemp while you play a game (or while running Prime95 as mentioned below), make sure nothing is getting too hot.
Inside your computer case, check that the rear fan is blowing out of the case and not in. And that the front case fans blow in, not out.
Memtest86 is fantastic take peoples advice and use it! Another great program is Prime95. I would get both for future burn in sessions. For Prime95, run the "memory blend test". That will find errors pretty quick. [but memtest86 is great so either one].
Then check all other drivers. Did you do a clean install of windows 7?
nevermind didn't notice the guy above already recommended Prime95, so I got nothing new to add.
" And here's a few good reasons why http://www.softsailor.com/news/34789-starcraft-2-a-disappointment-7-reasons-not-to-buy-it.html now the last reason about the chat room I'm sure they're fixing. But 60 bucks and only one campaign? No LAN? No thank you. Battle.net and DRM be damned. "
Just for the record, can you list other games you ARE willing to buy?