Let me be the first to welcome you to our forum, cpd934!
This question has been raised numerous times, with tons of replies. I would encourage you to do a search for "airbrush", then if you have any specific questions, come back here, and there will be a whole slew of helpful and intelligent people waiting to help you. MikeV is our airbrush expert here.
Badger, Paasche, and Iwata seem to be the leading candidates for best brush. Good luck, and see ya' around the forum!
Gip Winecoff