IF you have more than one computer sharing an Internet connection…

AND you plan on doing any kind of Peer-to-Peer file sharing (PtoP), Internet Games, Web serving, FTP serving, WebCams, IRC DDC, and Instant Messaging such as AIM, ICQ, Yahoo and MS Messenger…

THEN you’re going to have to configure your router to do something called “port forwarding.”

This web site will help you figure it all out.

(HT to saintlink)