Hi,
First off, are you using a Router or a hub to connect them? If you are using a router, all you have to do is right click "Network Neighborhood" and under DNS tell it to automatically assign addresses. Set up DHCP in your router and as long as DHCP is set on your XP machine, you're good to go. If you're using a hub, then you'll have to assign static addresses since a hub cannot run DHCP and automatically assign addresses. If you have little or no networking experience You're going to need to do some reading to learn more about what, how, and why you should do this. I'd translate it to normal human english for you, but my Universal Translator is offline at the moment.... ;-)