airport problem

I have the latest version of the mac book pro and use a dlink router to connect wirelessly to the internet. My computer will only connect to the internet when I am within 40 feet of the router. My brother has a toshiba computer with windows software and uses the same router to connect wirelessly to the internet. He can connect to the internet with almost full bars everywhere in my house. Is there something I am doing wrong that is preventing me from having more connection strength?

Such issues are always a bit hard to diagnose.

You might look into changing the routers channel. This would be described in the router manual. Remember to shift it 2 steps in either direction. Example: if your channel is set to 6, use 4,- or 8,+.