What you will need is a normal Cable router, without ADSL modem.
The NTL modem will plug into the router Internet port and then each PC will connect to the router.
You can get a Linksys Wired router for about £25 or you can go for wireless routers. This guide here reccomends both wired and wireless routers that work on the NTL network:
http://www.cableforum.co.uk/board/sh...ad.php?t=33018