A. Windows 2000 includes the utility RUNAS.EXE which allows you to run a program as another user without having to log off. This is most useful for Administrators who may need to run a single command as an Adminstrator.
The basic usage is:
C:\> runas /user:Administrator@savtech.com regedit.exe
C:\> runas /user:savtech\Administrator regedit.exe
Both the Windows 2000 naming methods can be used, the 4.0 style
"domain\user" or the Windows 2000 User Principal Name (UPN),
Full help can be found by typing 'runas /?'.
After entering the runas command you will be prompted for the password of the specified account, e.g.
C:\>runas /user:Administrator@savtech.com regedit.exe
Enter password for Administrator@savtech.com:
Attempting to start "regedit.exe" as user "Administrator@savtech.com"...
Another option would be to install the telnet service on the machine and you could then telnet back into the machine as the other user, run the command without having to log off the main user.
You can also shift+right click on an item and choose "Run As" from either Explorer, Desktop to bring up the Run As dialog and allow you to specify a user/password.