Not a n00b to forums, but a definite n00b to biking. Been out biking w/ some friends (both mountain and road) and I prefer mountain biking. I own a 15 speed Magna that weighs a ton, so I'm looking into better bikes.
My budget is around $400 and the Trek 4500 is looking very good right now, but my friend told me to look into eBay. Should I buy from a bikeshop or should I just get a used one from eBay? I found a few good deals, like a Trek 6000 for like $200US. I like the extended top tube that the high-end Treks have, for a lower, more aerodynamic riding position.
Personally, I found used mtb's on ebay to be a risky purchase. They get a lot more abuse than road bikes, and are more likely to have worn out components. I got back into cycling by buying a MTB from ebay, and ended up replacing just about every component within a year - wheel bearings, front fork were just plain worn out, brakes were old and parts not available when a brake lever broke.
$400 at a bike shop will get you a nice hardtail/front shock bike, nothing fancy, but you won't be buying parts and paying for repairs every other weekend.