Good entry urban / mountain bike?

im looking to get a new bike, ive mostly ridden bmx but i want a nice mountain bike. no cheap walmart stuff. i want to stay within a reasonable price range, under 350 (im looking at used bikes on ebay craigslist etc). im want suspension up front and hardtail. theres a diamondback response (2007) on ebay ive been looking at, clean, hardly ridden. also a trek 4500. what do you think?