I cannot go pass the logon screen, forgot password, password unlocker would not run. which system file stores the passwords?
You might have to hit the F8 to boot up menu mode and try system restore to a date before you set up a password or if not the only think I can think of is to reinstall the OS again. There is a password recovery option in User accounts to make a backup of your password in case you forget it! I would try going to the microsoft support site and put in MS Vista Forgotten password!