My reply
Hey, your problem could be a wide range of things including hardware and software there is only one way of finding the problem: process of elimination...
Start with software (You don't need any technical skills for this)
1) Reinstall Direct-X
2) Reinstall Display drivers, remove any redundant ones.
3) Reinstall the games ( I doubt it's the games, the law of probabilty told me so

)
4) Reinstall Windows ( Do this only when you have tried everything else, windows is usualy just 10% chance of being the problem)
Hardware (You need some experience with hardware otherwise I wouldn't even recommend you try this) Test your effort after each step...
1) Remove any extra pci cards you are not using now, Modem cards, sound cards ... etc. Except your display card of course.
2) If you have two ram modules remove one, test, swop them, test. Otherwise use another module you know is working. (You can also download a memory tester, and not get your hands dirty)
3) I think from all the PC's I have worked with the chances are good it's the display card, see if you can find another one to test your PC with.
4) And lastly, I have found AMD CPU's prone on giving blue screens as well (like ram), try another one on your M/B.
5) If all of the above fails you'll have to try another M/B as well, preferrable the exact same type. (I believe at this point you should rather take it to your computer vendor because it should still be under warrenty, they would basically do all of the above for you, and claim responsiblity if they stuff up)
Good luck man.... (Too bad you got yourself an AMD :dead: ... AMD = issues)