Thanks for all the info. I run an internet mail-order satellite TV business so I understand about cable. I'll take a selection of "F" connectors in case I accidentally knock the plug off while passing the cable through the wall.
I'll leave the length alone. If I can borrow the tool and connector I'll go the ethernet cable route instead. my problem is that I have to run a connection out through the living room wall, through the garage wall and into the back room. The NTL guy didn't want to do it because it was "awkward". Hmm, I wonder if Maplin stock the tool for fitting ethernet cable plugs. What are they called - HC45? Of course *I* stock the darn tool but my warehouse is 50 miles away in the opposite direction.
It's normal to leave Apple Macs on 24/7 so hopefully the IP address won't change for a long time!