Sharring internet connection with computers on my network

Ive seen to many things about this and i want one strait answer. I have 2 pc's in my home. One running Ubuntu 6.06 and the other Microsoft Windows XP Home. We are connected via an ethernet switch. I would really like to use DHCP to do the Ip address assignments but if thats too hard for this dont try it. I am using Firestarter as a firewall but i can uninstall it if need be. Thanks for the help