airport drops constantly

My wireless internet will work for about 5-10 minutes then stop working. It can see the wireless network, says it is connected, but no internet. I have tried moving to different rooms, different routers, different buildings, and it still won't work. My wifes windows laptop works everytime and stays connected. I am sitting 14 inches away from the linksys router right now and it doesn't see the network, but my wife is 6 feet away and surfing wirelessly right now. Ibook used to work perfectly, then one day just stopped working, does anybody have an idea as to why?