aka Hacking Your Windows Systems
If you need access to a local system (that is, you can lay your grubby little hands on it) that is not part of a Windows Domain, or you need local account for administration or repair purposes (like you need to work in safe mode without a network), the
Offline NT Password Reset and Registry Editor
Offers both boot floppies and boot CD's that allow you to clear the local administrator's password. This is of limited usefulness on an AD Domain Controller as it resets the Machine Account, and not the Domain Account, which is what a DC is interested in.
Unlocking NT/2000 Servers (Domain Controllers)
This set of directions are meant for the experts - but he makes it easy for just about anyone who's comfortable in front of a computer to follow. Requires physical access to a DC. Remember, any computer I can touch, I can own. This goes for most anybody else, too.
Resetting the Administrator's Password on a Windows 2003 Domain Controller
This is for Win2k3, but will likely work for Win2k also. It requires a bit of work and again, requires you can be in front of the server. Also requires a few more applications, which the author kindly provides links to.
If you use this info to gain access to stuff you shouldn't be accessing, or even just for general meanness, you can be fired, and even go to jail, which you would deserve.