I recently reformatted my room-mate's hard drive because of a significant instability problems, traced back to a bad original Windows installation (so bad that we couldn't upgrade to service pack 2!) Finally got everything up and running, and it's performing dozens of times better. The only problem was an intermittant crash with one online game, but we didn't think TOO much of it, since several other people had been reporting the same thing.

However, today it not only crashed the game, Windows completely crashed to a blue screen. He didn't get a chance to write down the entire error code, however the file being used at the time was ati2cqag.dll. ATI is the video card, however I don't believe it's the drivers, because I have the exact same card and the exact same drivers, and I've not had such a problem. Could it be just that same random crash, that this time just happened to take Windows down with it? Or was there a more significant problem? I'm also attaching the memory dump file.

It could be the video card on its way out...
I had a blue screen a few months ago and took out all the ram and replaced it with new ones... It has never done it again..
You should take the video card out and use the onboard or another video card to test it..

I did a memtest86+ full test last night on my memory, and everything is healthy, I've swapped out the videocard with my roommates (the exact same card) and I've had the same results happen to me. I've also been told by a computer tech friend, if it was the VRAM, I'd be noticing crashes much more often, but its only far an in and few and only happens sometimes.

It doesn't mean anything. Two identical cars rarely break at the same mileage.
Just make sure, the error happens again, write it down.