Finally I find a site willing to discuss the cheaper bikes geared towards beginners. Thank you

I've read some of this thread, but it seems most are in the $600 range and I really need something closer to the $3-400 range, so I'm going to go ahead and post.

I'm a college student ready to upgrade an 8yr old GT outpost trail to something with shocks (a hardtail) and gears that are a bit more reliable (I'm sure mine could be again with some work, but I really am in need of some suspension as well). I will mainly use this around campus, asphalt and cobblestones/pavers (hence one of the reasons for shocks). BUT, campus entails 23000 acres with many many trails and dirt roads open to bikers. I'd like to join a few friends for some adventuring and I think the addition of shocks and newer derailler technology will help me stand those excursions .

Essentially I'm not an avid mountain biker and am not sure I'll become one (I'll cross that bike bridge if and when I come to it), but I want something that is reliable on medium trails.

I've looked at Treks, Giants, and Gary Fishers primarily (I've heard the bad things about GT's quality since my bike's days, so have pretty much ruled them out). Of those I've found I like the Trek 4300 the most followed by the Gary Fisher Advance and the Trek 3900 (both nice because they come in a women's specific model which I may find I need being on the petite side). I've also looked at Giant's Boulder, but for some reason am not as thrilled with them.

Any thoughts on these other than make sure to ride them all (I'm working through two local bike shops and will probably buy from one, and so far am getting good service from both)? I'm specifically concerned with the deraillers and shocks as I have no knowledge in that area and that seems to be the big difference between the bikes (frames all having lifetime guarentees, weight being the same, etc).