You're close to some of the best mtb trails on the East Coast. There are also a lot of very good bike shops in your area. Go to as many as possible, talk to the folks there, see what they have in your price range, test ride a bunch of bikes, and buy the one that's most comfortable to you. I recommend you start your search over at Sycamore Cycles in Pisgah Forest, they're a cool and knowledgeable bunch.