I just bought a used road bike and it looks like it has MTB Shimano clipless pedals. Will this make a major difference in the ride? I still need to buy road shoes, will the MTB fit on road shoes? Should I break down and buy road clipless pedals instead? Nashbar has a good sell on some and don't want to miss it if road clipless is the way to go. Also, if anyone has any recommendations on road shoes please feel free to post.
Pedals don't make much of a difference in ride, no. You can use SPD's on a road bike, and the cleats either fit or you can buy an adapter plate for your road shoes (for example, you'll need an adapter plate for Sidi, but others like Specialized have the two-hole SPD cleat pattern). If you stick with it (or need more float than SPD's provide due to knee soreness) you might want to think about road pedals.