NAT with Vigor router

Hi I have a home network of 2 boxes both running 8,1. I have ntl cable modem and a vigor 2200E router. I have tried to set up NAT so I can acces the internet between the two. So far I cannot get internet access from the second machine, If I run knoppix on the second box it does work. The network is ok as I can ping between the two boxes. I'd welcome some advice as to where to look to change anything on the second box to get NAT to work with SUSE. Any clues ? TIA mike