Joe - XP is software. Your internal speaker runs from a connection on the motherboard to the speaker. Now, most sound cards have a connection so you can run a wire from the motherboard to the speaker.

Justa - It can be done, but I have an idea that might make it a little easier. Look for Linksys Cable/Dsl router with a 4 port hub. They're about 130 bucks or so, right now. This handy piece of kit acts as your network hub and internet shares your computers. Very easy to use and also acts as a firewall.