From what I've read, it seems there might be a slight issue with Apple's airport driver, but it's also a well known fact that Apple laptops (even the older models) can sometimes have their airport cards or antenna come loose. If I get up the courage to actually open my macbook, I'll need the following tear-down guide to safely do so, so that I can reseat the antenna connectors and airport card itself.

http://www.bukisa.com/articles/68749_install-or-upgrade-the-airport-wire...