Logon – No Administrator Password ?!?

I seem to be having a problem with my newly inherited “NT/Win2000 Server”. Unfortunately, prior to my employment the previous Admin had left to live the sweet life in Thailand.
My problem being I have a server with 40 machines hanging off it. I have NO Password for Administrator access, and none of the employee logins is granted “Console Access”, so short of a format which will be costly and time consuming (in terms of the company), I would like to know if there is some way to find a ‘backdoor’ into Win2000 Server with Administrator access?
Sorry, this is probably an easy question, but I’ve been landed with this problem and I have a network full of viruses and servers with no passwords to fix.
Thx