What is Win2000 password file extension?

We have a server that has recently been set up in our plant. The problem is, the guys that set it up password protected it. The password they gave us, does not work. A man from the company that installed it has come down and cannot get into the computer. I know that in Win 95 and 98 the password files end in .pwl. But I don’t know what they might end in for Win 2000. Does anyone know what file extension Win2000 uses or any other way to delete the passwords and redo it? I don’t know ANYTHING about Win2000 and we are really stuck.

Thanks in advance.