Just get some of the Mountain bike magazines and look for the Writeups on the £XXX bikes that they do. Don't know where you live but if you can get to one of the big bike shops- NOT HALFORDS- and see the range that is done ther- but look around on line for better buys

By far the best bet though- is to find a good local shop and see what they suggest.
Couple of Links below

http://www.merlincycles.co.uk/acatal...lin_Bikes.html

For a range of mail order bikes

and

http://www.evanscycles.com/

For a large chain of shops.