Mountain Bike purchasing advise

Question
George, I have been looking into purchasing a new mountain bike for a while now.  My problem is that there are so many models to choose from, I don't know how to narrow it down myself.  My main concerns are durabilty and cost.  I'd prefer to spend less than 500, at most 600.  My last bike was a Schwinn Aluminum Comp sold at Wal-mart.  It held up ok untill I started riding more aggresively on trails.  Then I started having problems with bent rims, broken derailers, etc.  So I need a tough bike.  I have been recommend the Trek 4500, Gary Fisher Marlin.  Do you think these bikes will serve my purpose?  Do you have any other bikes in mind that are in the same class or one class higher (not over $600).
Thanks
-Nathan

Answer
Hi there,

Actually I do! Try the MARIN Novato bike. I have one (souped up) but stock its still very nice. Super light aluminum triple butted frame, double butted rims, slicosaurus WBT tires, WBT ROCKET V seat (Consumers choice award)www.mtbr.com, and all kinds of other stuff. I pais $700 (I know you are looking for $600) but pay the extra littl bit and im sure you will be more than happy. You can also check the bike out at www.marinbikes.com

thanks for the question!