which should I buy

Question
I am just now getting into mountain biking and have narrowed it down to a used 2005 cannondale f400 in great looking condition. He is asking $400. or I am looking at a new stock 2008 gary fisher wahoo for $500

Which is the best deal and fit for in town as well as trail riding?

Answer
Okay, remember bike feel is a very subjective thing.  You should first look to which bike feels the best when you are on it.  Both are capable off-roaders and will handle like mountain bikes on the road.

Assuming all things are equal (that both bikes feel good), I am partial to the Cannondale because of the frame quality.  It will tend to be a bit  more sporty and, I believe, better made.  My philosophy is that the one bike part that you can't replace for cheap is the frame, so that is the first focus whenever you are shopping.

In addition to that, the Cannondale is less expensive, so I think the best deal competition goes to Cannondale.

As for the components on the used bike, the bike owner can tell you the condition of those, but as I said, most parts on a bike can be replaced fairly cheaply, so component wear is only a factor if all of them need to be replaced at the same time, which is unlikely.  

One other thing you might do if you are going to buy the Cannondale.  Take it to the local bike shop and have the mechanics take a look at it.  It shouldn't cost more than a couple of dollars (or even be free) and the mechanic will be able to do what I can't do over the internet: Diagnose any problems.

Good luck, I hope this has helped.

Graeme

P.S.: Years ago, I narrowed a mountain bike search down to a Cannondale 600 vs. a Gary Fisher Hoo Koo E Koo.  I bought the Cannondale, raced and loved it for a year and sold it the next year (I was given a Litespeed) for nearly the same price.