make sure you have the service install (not installed by default) and in terms of networking side, you'll need to open port TCP 3389 and point it to the server.
without purchasing TS license, you are only allow to have max of 2 connections at the same time. I will never use it for more than 1 connection since it disconnect and kick you out sometime if you connection is not good and you'll need the 2nd logon to clear it out.
if $$$ is not an issues, Citrix is the way to go.
Albert
can anybody tell me how can I allow somebody to connect to a server using the windows terminal services connection? I've never had to use this before and I'm kind of confuse with it... my operating system is windows server 2000

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic