Originally Posted by
Artkansas
I would tend to go with the recommendations of a hard-tailed mountain bike. Though you might want to go with street slicks.
1) You don't need suspension, keeps it simpler.
2) Good mountain bikes tend to have components selected with eye towards being abused.
3) 26" tires are available at almost any Walmart
4) Low profile, not as desireable by thieves.
Others of the LDS persuasion have outlined a good overall view.
I personally used a 20 year old Specialized Hard Rock as my exclusive transportation for 3 years and it held up wonderfully. A used bike can be good, just make sure you have it blessed by the local LBS that it's in good shape.
Don't mean to confuse you, but this is a fine option, if you add fenders and a rack. Keep a thick pant leg strap with the bike, too, to keep them out of the chain. Nothing wrong with using a mountain bike, but spend the $ on the transportation gear and mount up some slicks and you'll be fine.