To add to MGP & Indians' excellent advice:
Suggestion for a cheap router:
Linksys BEFSR41, £32.74 at Amazon. It's a wired 4 port NAT router. If you need to connect more than 4 devices to it (although you are only really allowed to connect a maximum of 3 under the AUP
), you can plug a hub into one of the router's LAN ports to extend it.