Limit the number of connections

Hi everyone.

I am quite new to Active Directory and Services.
I need to set a user such that he can only log in one machine at any one time, ie. single log-in, not multiple log-ins. I used to be working with Netware servers and I know that function to limit the number of connections exists in Netware 5. How about Win2K server? Does anything like that exist? Maybe anyone of you can enlighten me on this matter? I can’t seem to get the answer from the books.