A little google goes a longggg way my friend. I found this after typing 'backtrack 3 wireless' into google.....first page. If you look for your wireless adapter, you can see that that there is a link to your specific problem.
I can't post links because i haven't posted enough, but just do a google search and you should have no problems finding it.
Do a little reading on that, and you should be fine.
I've been staying up to date with backtrack since its release, and this is the first post I've ever done and it is to re-iterate the fact that GOOGLE IS A HACKER'S BEST FRIEND!!!