A switch requires a router. A switch doesn't have DCHP, so it can't assign IP addresses. It also doesn't have a WAN port, so it can't route packets to the Internet (actually, it can't route packets period...it's not a router!). A switch is basically an add-on that gives a router more ports. Get yourself a wired (or wireless, but it needs to have wired ports as well) router (like the Netgear WGT624v3, LinkSys WRT series, etc) and wire like this:
||Wall Cable Outlet||-------coax cable---->CABLE MODEM -----ethernet--->WAN-ROUTER-LAN-------ethernet----->ANY port on SWITCH------ethernet cable(s)----->PC, XBOX, etc.
You need a standard LAN cable (not crossover) to connect the switch (any port) to the router (any LAN port). Then the 7 leftover LAN ports (assuming 4 port router, 5 port switch) all work as LAN ports for computers, consoles, etc, and the router's internal DCHP server detects all of them. The modem must be connected to the WAN (Internet) port on the router.