I have a prblem with RDC from outside to Server 2003. I can connect to RDC to Server 2003 from inside. I tried to RDC toanother PC from outside, and it was OK. The problem is only the Server 2003.
So RDP by default uses port 3389, but if you have multiple computers you wish to RDP to, you will want to configure a unique Port for each of these and then configure your Router to forward the ports to this.
Also please do yourself a favor and make sure your running RDP version 7 so your data is not being sent around in clear text