Mountain Biking - Buying my first bike

I was refered here from the general forums as maybe this forum might have some people with more specific knowledge on these bikes.

So I've gone out and done some research. I'm looking into these bikes:

From a local Bike shop:
Gary Fisher Advance (lifetime on frame)
http://www.fisherbikes.com/bikes/bike_detail.asp?series=trail-classic&bike=Advance
Trek 3900 (lifetime on frame)
http://www2.trekbikes.com/Bikes/Mountain/Hardtail/Alpha_Aluminum/3900/index.php

From a second local Bike shop:
Raliegh Mojave 2.0 (5 years on frame)
http://www.raleighusa.com/items.asp?deptid=11&itemid=283&va=0

From Dicks Sporting goods
Mongoose Sector (30 days or 3 years for $50)
http://www.dickssportinggoods.com/product/index.jsp?productId=1968596&cp=1160099.2015170&page=2&doVSearch=no&pageBucket=0&parentPage=family

Any thoughts? The mongoose definately gives me the most and is I believe also the cheapest but from Dicks (which actually does have a guy that does the bikes and services them etc. but nothing like a real bike shop I don't think) The Trek 3900 is pretty tempting.

The best advice is going to be stay away from any bike from Dicks or any place like that.

The next best advice is to go test ride the bikes from your local shops then decide which one you like the most. To me a five year warranty is just as good as a lifetime considering that I doubt I will ever keep a mountain bike for five years. Since the warranties are non-transferable it won't matter how long the warranty is if you sell the bike in a couple of years.

First things first, Welcome!

You should have a look at this (http://www.bikeforums.net/showthread.php?t=56148) first before you go much further. Its a thread, a loooong thread, that covers pretty much any question you might have and a bunch more you hadn't thought of. Second, whatever you do dont buy a bike from a sports store, or online. The first will sell you junk they can barely assemble let alone back up with service or knowledge, the second will see you buying gear you cant use that looks good online but never quite fits/works ect. Its not that there aren't good deals online but that a new rider is not always going to make the right choices without being able to see and ride the gear in person. Third, before you lay the $$$$$$$$$ down , ride, ride everything you can get your hands on. Everybody is different, what works for me may not work for you, the only way to know if a bike is right for you is to ride it. Good luck.

I'd go with the fisher advance. Raleigh make crappy bikes.