I am looking for a new bike and I just stumbled upon this site, so it looks like a good place to start. I am looking for a bike that I can use for light trail riding as well as neighborhood riding (with my wife). I have been given a $500 budget, so I can't really get crazy, but I'm not in need of anything special.
Just by browsing the internet over the past few days I have narrowed it down to a few bikes in this price range. Are any of these any good? Am I going in the right direction? Any help would be appreciated.

1. Trek 4300 --- $494
2. Specialized Hardrock (disk) ---$500
3. Specialized Rockhopper --- $519
4. Iron Horse Warrior Expert / Comp (06) --- $500 / $539