Logoff users automatically

If you only want to remove these users from the network, set up logon hours in User Manager for Domains on the accounts you want to control.

Then in User Manager,click Policies and then Account and check the box near the bottom that says "Forcibly disconnect remote users from server...".

This should diconnect any defined user when the allowed logon time expires.

Use tools provided in the NT Resource Kit. Logoff.exe does exactly what you are looking for. You can use AT or WinAT to schedule the logoff, and you can choose whether or not to prompt users to save data before the logoff procedes.

You might find a lot of other useful goodies in the Resource Kit. Its contents are listed at http://www.microsoft.com/TechNet/subscription/masterlist/na/cd6.asp .