[Halcyon]

As Paul said, get yourself a router.
Linksys routers are quite popular and very easy to set up.
A wired router costs about £30 and wireless routers around £40-60

To give you an idea of how it works..... The Internet (NTL modem) plugs into the router, and then each computer connects to the router either via wired ethernet cable or if it is a wireless router, a wireless card.