I installed a new C: drive, fresh Windows XP SP2 setup, fresh Firefox setup, restored my mozbackup, everything seemed OK until I tried to log in to a known site. It appeared that my passwords list was still empty.
I unzipped the backup, copied signon2.txt to my firefox profile, restarted firefox and my passwords were back.
It took me only seconds of googling to find out that a mozbackup is a zip and some more seconds to find out which file to place where (thanks Google), but I don't understand why mozbackup wasn't able to either do this or to report what went wrong.
Logged In: YES
user_id=980800
Originator: NO
Did you use latest version of MozBackup?