I had the exact same issue with my system. After spending many hours surfing the internet trying to correct the problem on the laptop, I realized that, at least in my case, the problem was with the AT&T 2wire wireless router.
I tried installing multiple distros, including Crunchbang, Ubuntu, Fedora, Mint and more, and had the same issue with the wireless in each distro while using the AT&T wireless modem.
The odd thing, was that my wife's XP Desktop, and her Vista laptop both worked fine with the new wireless modem.
After much frustration and scratching of the head, I remembered that the wireless was working on the laptop before I installed the new modem, so maybe the problem wasn't with my laptop.
I removed the new wireless modem and went back to my original wired only modem and wireless router and voila! - the wireless was working again.
I called the Telephone company and sent the useless modem back to them.
Try taking your laptop to a local hotspot and seeing if the wireless works there.
If you find that it does, then at least the pain I went through will have benefited someone else.