Ophcrack is a Windows password cracker based on a time-memory trade-off using rainbow tables. This is a new variant of Hellman's original trade-off, with better performance. It recovers 99.9% of alphanumeric passwords in seconds

http://sourceforge.net/project/showfiles.php?group_id=133599

FREE HTA based utility that uses ADSI to remotely change the local administrator password.  Manage either a single computer or a list of computers:

http://jdhitsolutions.com/pwdman/index.htm