YAY! I did it!!!! They're gone! And the problem wasn't in Gimp. Even after deleting from the registry, and deleting the physical files in C:\Windows\Fonts, the files are still there. Windows will refuse to show them to you evermore, but they are, in fact, still right there under your nose. So, this is the way to get rid of these fonts:

1. Write/type/print (but have a hard copy) a list of all of the fonts you want to get rid of.
2. Go to the Fonts directory and try to delete them. You'll be able to simply uninstall about half of them.
3. Run -> regedit -> HKEY_LOCAL_MACHINE -> SOFTWARE -> Microsoft -> Windows NT -> CurrentVersion -> Fonts : Delete the keys for all of the fonts on your list.
4. Download and burn to disc an image of the latest Ubuntu. Restart with the disc in the tray, and hit the TRY button (this will run Ubuntu without actually installing to your computer).
5. In Ubuntu, go to Places, then Computer, then the drive with Filesystem on it. Go to Windows/Fonts and delete the files for the fonts on your list.

Now they're ACTUALLY gone. Gotta love linux. M$ knows better than you do, but linux lets you fix their crap.