2Liter,
You can certainly use an MTB to tour/commute with. I have an '89 Rockhopper Comp with a Scott AT4-Pro bar, 150mm stem, racks, lights, bags, etc. This bike has a little over 100k miles and still rides good. Take the advice above. Keep it tuned, get some slicks or minimal tread tires, and enjoy riding. I just returned from a 435 mile, 6 day ride accross Missouri. Loaded, self-supported tour. It was great. A couple of pics: http://users.solve.net/~jharte/Bike/...Katy-Trail.jpg, http://users.solve.net/~jharte/Bike/...Katy-Trail.jpg, and one snowy pic: http://users.solve.net/~jharte/Bike/...Parkbench1.jpg. After you get your bike the way you like it..."just being there" is what it's all about. Good luck!