Repairing an installation will definitely not destroy any accounts, *unless* the accounts are already toast, which would make the matter a moot point anyway.
Yeah, the accounts are fine, as far as I can tell. I was able to view information about them and bruteforce their passwords, so at least the SAM and other stuff are intact.
I don't have access to a computer to get that going right now, unfortunately, but when I do I'll be sure to let you know how it goes.