I found this in a few different places around the 'net - hopefully it's helpful:
Access the Administrator Account from the Welcome Screen
If you are at the Welcome screen and want to log on with the Administrator account, but it's not listed:
- Press Ctrl+Alt+Del twice to bring up the Windows 2000 logon window, which then allows you to log on as Administrator.
Logging on at the Welcome screen is not available on computers that are members of a network domain.