And to provide a little more info on the problem....
I use pump as it was (for whatever reason) installed with Debian Woody. Changing my dhcp client would require a net connection....
One thing I found out (by STFW: http://www.linuxquestions.org/questions/history/28208) was that Linux broadcasts it's MAC address in a different way to Windoze, so the suggestion was to reset the set top box, bring up the interface, then re-register on NTL.
Fine, only there's a problem. I wish to use a dedicated router/firewall (www.ipcop.org). I'm fine with transferring NICs between computers, however the ipcop box *could* ping outside (having transferred the NIC, and resolve hosts. So that kinda throws that theory away. Unfortunately, clients on the internal network can't resolve hosts or ping outside going through the ipcop firewall. (also, ipcop has now browser capable of doing the register process anyway. in fact, it comes with no browser).
I know the wordwrap is fscked, btw, as soon as I get connected in linux I'll use a proper mail reader.