Quote:

is there a way to access the remote registry of another user with a different username/password?


Is it this what you are looking for?
- The NTUSER.DAT file should be closed (the user should have logged off)
- Connect to the computer (p.e. "NET USE \\ComputerName Password /USER:ComputerName\AdminAccount")
- Open regedit, position on HKEY_USERS and go to File -> Load Hive...
- Browse to \\ComputerName\C$\Documents and Settings\UserName\NTUSER.DAT, provide a name.
- Do not forget to UNLOAD HIVE afterwards, before user logs on again