Woohoo!
Yes, it was indeed the modem that went tits up. Just has a visit from one of the NTL guys. He ripped out the old modem, slapped on a brand new one, and voila! Internet again! God, yesterday without the net was unbearably slow. I ended up having to get my xbox out just to make the time pass quicker.
Now comes the task of having to piss around resetting the firewall and everything.