I recently built a new computer for my son (specs below) and each time I tried to install windows 7 I would get past where it lets you select the drive partitions and it would go to copying windows files. Then during expanding files each time at a different spot my computer would quit. The monitor would go black and the drives would stop chugging away but all of the fans would stay active. I would have to hold down the power button to restart. I've already solved the problem having tried swapping ram and disconnecting all of the peripherials. I read the forums here and that is how I came to the conclusion that it was a heat problem. The setup would not stop each time at the same place but at different places during the installation (and yes I tried XP as well thinking it might have been a driver issue). Comes to find out that the old nvidia 9800gt video card that I had taken from another computer was overheating. I replaced it with a new nvidia 9800gtx+ and the computer now runs smooth.
Western Digital Caviar Black 500GB 7200 RPM 32MB Cache SATA 3.0Gb
could be the mobo, do mem test with one stick of ram, then do test again for every slot for the same stick on my mobo slot 1 and 3 died on me had same problem and thought it was heat too, guess i was wrong