Can I force a logon with Windows 98?

I help oversee a small network – about 70 pc’s. The client end uses Windows 98, and the server end uses Windows NT 4 and Windows 2000 Server. Users on the client end keep running into trouble because they skipped the logon screen and are working on their PC, not the network. (Yes, I’ve explained it to them many times, and that’s OK.) Windows NT workstation forces users to logon to the network, is there any way to accomplish this with Windows 98? Thanks, Robert