just buy a hub or router and set everything to DHCP. Plug your internet into the hub and then connect all the computers into the hub. Set them all in the same workgroup using the internet connection wizzard (if Windows). Bobs your uncle.
most routers come with built in switch. it acts as a all-in-one unit. so basically all you need is a router. it serves as the DHCP server and this way you do not need a computer to be the server. all computers connect to the router and enable them to share an internet connection.