TRy Cool Edit Pro. You should be able to get a trial version from download.com. It has some good tools for removing noise, hiss, etc.
I'm using it right now to try and clean up the Minneapolis radio broadcast.
I'm working on putting together a decent version of this show. The radio feed dropped out twice so 'God Put a Smile' is cut off and they skipped Poor me entirely. If anyone has a decent version of this show, let me know.
Thanks!