If you can get a static IP get it. If not there are dynamic DNS services out there.
DNS is an important part of a website/domain. Someone types in
www.yourwebsite.com and the DNS resolution says "Ok,
www.yourwebsite.com is this IP address" and it goes there. If you don't have a static IP it will register the IP that you have at the time it goes live, then when your IP changes people won't be able to get to your site. If you don't have a static IP address, a dynamic DNS service constantly updates your IP address and will point people to your site regardless of how often your IP changes.
If you are running XP, it has a built in web server. Only problem is, it only supports one site. If you want 5 or more sites, your going to have to go to NT or 2000 Server, or a Linux/Unix based web server.
Either that or go to a hosting agency. There are millions of them out there. Check out the add on the front page of OC.com, there is an add for PowWeb. They are a pretty good host.