from personal experience...
I use a 2003 Trek 4500...i like it very much and it has a very sturdy frame...Ive used and abused it quite a bit and it must have a few 1000 miles on it now (MTB)...the stock components do not last unless well taken care of (and even then, some may not last)...ive had to change: cranck set (to deore shim.), rear wheel and hub (changed to LX shim.), normal stuff like cables/housing, tires (normal wear), all chainrings, all cogs, using XT brake pads syst. now...and...thats it...the seat is fantastic (comfortable), the bike is definitely on the heavier side for a hardtail (but likely like others in the same price range), the stock front derailleur (allivio!) is working great, if not as smooth as XRT, and XT ones, but effective (in fact, shifts faster than XRT with the funky dual use)....
The front fork works only in extreme situation in downhill drops (and works well then! does not bottom out)...not very active otherwise and feels like its not there, does not even bob much at all when standing up on climbs or any otherway...not really adjustable as claimed (I have the elastomer version, Judy TT)...Frame is made in usa too, if you care...lifetime warranty for frame (a big +).
If you're low on *immediate* cash, go for it, if it fits you well...otherwise id recommend going higher on the component scale to the 6700 at $750...it has all the quality components I wish I had now and more (and really good enough for any use short of pro. racing, and long distance races)...and would have been acquired cheaper in the *long* run if bought upfront with the bike...Do maintain well, however.
You realize, you WILL upgrade to full suspension in 2 yrs or so??? im in this very process, but will keep my current trek 4500...
good luck.