Thanks for the response.
Having to provision the once when I plugged the new linux box in was what I was expecting and I've never experienced this with anything before. I've been using broadband through an STB since 2002, when it came to my area, and I've been hanging a router off it quite soon after I got it. Infact the old RP114 is sitting on my shelf. That was when routers didn't have tons of plastic around them. It was great until I found that it didn't route UDP and therefore I couldn't use voip. Then came the move to RP614 then the FC4
To be honest of all the problems I was expecting, this wasn't one of them...