If you could skip the off roads and get a bike for roads and pavements use only. Then get a mountain bike for the future instead. When you want to do some off roads. Then you can look for a bike that is better for longer rides and is comfortable. Like a hybrid that is more of a road bike. Like the Fuji Absolute models and Jamis Coda models etc. If you want to save money. You can get a bike from www.bikesdirect.com and take it to a LBS and get it adjusted for around $50-$60.

http://www.bikesdirect.com/products/fuji/absolute_2.htm I got the same bike, but the 19 inch blue men model from them.
http://www.bikesdirect.com/products/...fe_latte_x.htm I got this model for my wife, but a 15 inch in women frame.

Both are very good bikes. Fast and light.