Windows 7 - cant believe that could only be a year away - One thing for certain is that someone somewhere will get a Blue Stop screen or the equivalent.
Seen no end on Windows XP - doesn't matter what version you have - has often been HD related - in one instance it required a reinstall of wireless drivers (on a newly built XP machine!), once it was caused by Hyperthreading being turned on - and thats the beauty of it could be one of many things.
Try different virtual memory settings(if you can in Vista), check everythings plugged together as well as it can be - try disabling things - like network cards for example and then playing a game to see if it still happens - your best hope (not short of deciphering the stop code ) is to try and narrow it down.
I would be screaming at the thing by now myself too - reminds me of how stable Windows 95 was out of the box