About a month ago, while trying to upgrade to Windows 7, I managed to wipe the partition table and in trying to fix it, created a corrupted table.
(incidentally, if you can’t update Vista with the latest service pack, you won’t be able to upgrade to Windows 7, so don’t bother trying without fixing your boot configuration. Turns out my problem was having a dual-boot configuration with XP)
I had backed up my key files, but I wasn’t keen on losing my nice Vista configuration. I posted the whole sordid tale on Superuser.
Happily, I managed to figure out what had happened, what I was actually doing at a low level (sometimes I am a little too lazy and do just blindly run commands, something that Raymond Chen despises), and completely recover. I figured I’d post a link to the solution in case anyone else has their own troubles.