I'm going to start digging around in the router config... however I have certainly not restricted the lappy MAC, and if a general restriction was in place, the desktop PC wouldn't work properly either.
The lappy works fine when connected to the router via a cable, just not via wireless.
I did think that maybe Belkin was just crap, but I have had the same problem (in another part of the world) with a Netgear router... so...
I find it astonishing that after so many revisions to Windows (from 3.0, which is what I started with), they still haven't managed to make networking a relatively simple and bulletproof task. just try getting XP to talk to Vista properly...