Trying to use port forwarding

Question

I am having trouble with port forwarding. I have 5 people in the office I need to be able to connect from home to their win xp pro machines in the office using remote desktop. I have the instructions to edit the registry and did so last night but I can only make a connection from outside the office on 3389. The pc who has 3389 gets thru - no one else. I must be doing something wrong. please help