I've backed up my files off the drive, and when I go home for the 3-day weekend coming sometime soon, I'm going to totally reformat the whole drive (both partitions), and reinstall everything from scratch. (and then stick in whatever stuff I backed up, some of it is the installs I'll need, a few config files, my mIRC scripts, my bookmarks.html, various assorted image files, that sort of thing...
Apparently what corrupted so much was probably attempting to upgrade my geforce to a higher revision and having problems with its install disk or something, although simple file corruption from a flaky IDE cable can't be ruled out either.
Ick.