Corey,
A great site to spend some time on in determining whether or not a Jordan is authentic, is
http://www.rareair23.com It has numerous examples of Jordan signatures throughout the years, and also gives decent advice on how to tell which signatures might be good, which might be forgeries, etc.
Go there and do some research, and it will be time well spent if you buy/sell/trade Jordans.
Take care,
Mike