As I said in other posts, the bike I have is a hybrid of sorts and would probably be referred to as a Cross bike, but when I bought it they called it a mountain bike.

The frame looks like a typical Cro-Moly road bike frame, except it's designed to take 2" knobbie tires and it has MB handlebar, shifters and brakes. When I bought it knobbies were on the rims but I immediately switched to 2" City Slicks (world of difference on pavement) and now have 1.5" Slickasaurus tires which ride a little better than the older slicks.

I like this configuration; it might not be as fast as a road bike, but it's comfortable and the bike can handle some abuse. As long as you don't need to be set for road racing, go with comfortable and tough.