I am just getting back into riding after a 12 year hiatus and need to upgrade badly. Most of my riding is road/paved trails with ~15% dirt roads(forrest service/logging). I would like to get into doing some single track riding. I have been looking locally and have a couple options.

Marin Pioneer trail disc for $529 http://www.marinbikes.com/2012/bike_...eer_Trail_Disc

Raleigh Talus 4.0 for $499 (comes with free tune-ups for life)http://www.raleighusa.com/bikes/moun.../talus-4-0-13/

Novara Torero 29er from REI $518.93 http://www.rei.com/product/825410/no...29er-bike-2013 (not in stock so no hands on experience)

I have also Been looking at a couple 29ers that look interesting. I am assuming that I will get a better bike with the above for what I want to do for riding.
Dawes haymaker 2900 $399.95 http://www.bikesdirect.com/products/...ymaker2900.htm
Mongoose xr-pro http://www.walmart.com/ip/Mongoose-X...-Bike/16913467 I get 10% off at WalMart, so the price would be $341.1.

I am a heavier guy at 5'10 225lbs if that makes a difference on what bike to look at.

Any other bikes in the $500 and under price range I should be looking at?