You need a router and 2 network cards(wireless or not?) to plug into your pc's, along with a few cords(maybe). You plug cable access into the modem, then port(cord?) out to router, where you port(cord?) out to your network cards in your PC if you choose wired. Very cableless is available and I have a wireless router, but I choose the wires as it is better security for me.
Wire(less) router and network cards.
I use a wireless B router with 2 out to my pc's and one out to my PS2.