In my opinion a DO can do a bit more than an MD. Both can prescribe drugs, both can do physical examinations, both can do referals, and both can specialize in different fields. What sets a DO apart? It's the manipulative therapy. Let me give you an example...
My wife was riding a bicyle and got hit by a car. She had to spend a day in the hospital and have a load of tests run. The MD's (a hospital attached to an MD school) put her on muscle relaxants (Flex er something). Everything was fine until I took her home and the drugs wore off. I ended up having to carry her down a set of stairs, and put her into the truck and take her back to the hospital. She was stuck in a ridged sitting position because her muscles had tightened up so much she could not move at all. The MD's at the ER gave her more muscle relaxants and sent her home. She was OK as long as she took her drugs (which had some other side effects.)
We then took her to the Clinic attached to Kirksville COM. When she went in she was walking (it was actually more like a hobble) hunched over and in obvious pain. When she came out she was walking almost normally. No pain. It took another treatment before she was compleatly "fixed." All of this was done without drugs. I had been an MD prospect up until that point. After that, I was decidedly DO. I have seen what the OMT can do.
Also, I have heard alot of pissing and moaning about how DO's are inferior doctors. If they were such poor doctors, why are they allowed to practice? Both DO's and MD's can have good and poor doctors. It's a fact.
Good Luck to everyone in fulfilling your dreams.