Having troubles connecting to the internet

Ok so here's the deal,

I have a friend from germany trying to use my network here in canada. I have a wireless connection at my house that I use to get on the internet. For some reason though he isn't able to. He uses a PC and it shows him that it recognizes the internet is there and it picks up the signals, but it doesn't let him connect. I've tried to enter the IPs manually and tried using ethernet. In both instances it doesn't work. He has windows XP, does anyone know of a solution?