I just thought I'd update the thread. Lets see:

- replaced RAM, problem continued
- replaced Shuttle system, problem continued
- replaced video card, problem...solved!

Damn ATI card was causing all the problems. I don't know why, either. Perhaps the Shuttle system didn't care for a card that didn't have that 6-pin power connector? All I know is that this card didn't work, but this card does. I've never gone with nVidia for some reason, probably because I liked getting cards made by ATI themselves instead of BFG or MSI or XFX, etc. But this card is impressing me. At the very least, the Windows drivers aren't the horrid mess that ATI's are.

So that's it. That was the problem. A bad video card.