Logging on without password

A woman I work with bought her old workstation from work. Her son was installing W2K over W98 and now, when the computer boots up it comes to the log in screen and defaults to to woman’s username but won’t accept her password. I have tried every conceivable combination of usernames and passwords from the office but none of them work. Does anybody know of a way to bypass the Windows login for this workstation? I’m trying not to re-install Win 2K and wipe out all of his data. (assuming that he still has data and didn’t wipe it out when he first installed W2K)