Well, he said that he changed some settings on the administration page and tried bout six combinations but nothing worked, so he had a feeling it was something to do with one of the cables. He went down to the car and bought up an identical dark blue ethernet cable (the one that came with the router, as opposed to the turquoise one that came with the modem) and used that. It still wasn't working so he tried resetting the factory settings and then cloning the MAc numer again. At some point alon this it started to work, though he said he didn't know what it was that he changed that done it. He tried the thernet cable again when he got home with his own router, and it is fine...
I am sorry I cannot be more specific, I was purposefully staying out of the way when he was working on it, I was already fed up enough with it.
Once it was set up I had no problems linking my Macbook, DS and Wii up wirelessly, and I have set the security on it so that my neighbours aren't gtting free internet
so, I feel, at least I acheived a little something painlessly to make up for all of the trouble at the start
Thankyou again for all of your help guys!