I figured it out. Recently I upgraded my RAM. I had 2x corsair 1gb, then 2x Wintec 1gb....two different brands. It worked fine when I had XP, but it was then crashing Windows 7??! Weird, I know. I figured it out because I booted off the install disk, which made me crash and I thought "maybe it's not the OS"
So...I guess I need to buy new RAM, again, but this time the same brand? Windows 7 is now working, but I only have 2gb of RAM installed...hmph....how sad.