Hi Neil Hester and a great big
to the site
1. have you removed all the NTL software from the computers. Its not needed now you have the router.
2. can you ping from the pc's - in a command prompt window type ping 194.168.4.100 and tel us what happens.
3. make sure you disable any ICS or firewall software on the pc's - you dont need them behind the router.
HTH