First make sure his laptop can pickup other signals - so that we can determine if the issue is your signal or his laptop.
My first thought is maybe his laptop is a B wireless card. I'm not sure about the new N routers, but with the G one I have it has the option of broadcasting both G and B. And there is an option just to broadcast one signal. WIth an N router i'm wondering if it just broadcasts N and G, or does it broadcast all three? Check that first.
The the two easiest things would be to ensure he can use wireless elsewhere and to ensure your router is broadcasting N,G and B.