After losing about 40 pounds, I wanted to take up a sport for the summer, so I got myself a Schwinn MTB from Wal-Mart. Rode the heck out of it, and liked it so much, I decided to go road.
I got a Trek 1200, shoes, tights, jacket, helmet, gloves, a bag, bottle, pump, and framepump, and slowly built up distances until I went 25 (the short route) on the NYC MS Bike Tour.
The transition was easy for me, since I had ridden what used to be called a "ten speed" most of my childhood with my dad and my friends. Now, I can ride for quite a bit and be comfortable. I love my road bike, but every once in awhile, I jump on the MTB for a change of position and pace.