SAM (Security Account Management)
Windows is smart and it opens and holds on to the files, and its one the the few things windows does when it starts up. Anyway, think smart, get it before windows loads (boot disk). If you have NTFS try getting a NTFS reading boot disk.
Passwords for the local machinein some Deep Deep encryption. Right now, there is no known way to decrypt except for Brute force.
the following information should only be used if you have lost your (YOUR) password and dont try to get into anyone elses machine.