Unknown Administrator Password

I recently got a call from a small office that is using Small Business Server 2003. The Server was installed and configured by another person who is now MIA. The office does not know the administrator password to the Server, and is, consequently, not able to log into the Server although they are able to access their files through the previously setup mapped drives.

The former consultant did not leave any documentation, and they also do not know the passwords to their router, firewall, etc.

Short of spending big bucks for a program like Winternals, are there any suggestions on how to recover or change the admin password so they can fully utilize their equipment?