Alright, lets get the facts straight and I'm referring to "McDoctor's" post specifically.
If you go to a DO school, and would like to eventually practice in these 5 states (Florida, West Virginia, Michigan, Oklahoma, and Pennsylvania) the AOA ("American Osteopathic Assocation"....not the AOA that MD's refer to which is there honor society "Alpha Omega Alpha") requires that a DO complete an AOA-approved INTERNSHIP. Depending on what region of the country you end up for med school, you may actually find that the DO internship is better/more convenient to do than traveling elsewhere just to do an ACGME-accredited (ACGME=MD, fyi) internship.
Now let's say (for whatever reason) the ACGME-accredited internship is actually better/more convenient, THEN you can ask the AOA to accept your ACGME-accredited internship to fulfill their requirement to practice in those 5 states that I mentioned above. This AOA rule (or "loop-hole") is called Resolution-42.
Please be aware that MANY DO's do ACGME-accredited internships and then apply for acceptance of their internship through Resolution-42. It's commonly done and for the most part, fairly easy to get the waiver/acceptance (i.e. almost everyone gets approved). It's really quite simple so don't let MISINFORMATION sway you from making such an important decision in your life.
I'm no expert on Psychiatry but from being on SDN for years and in med school, I can tell you that you will face VERY little bias (and mostly like none!) if you decided that Psychiatry is your passion. Psychiatry programs don't really care if you're an MD or a DO. Talk to Psychiatry program directors and they will confirm this fact.
To improve your chances of matching at your #1 choice Psychiatry program, do the obvious (and this applies to anyone, MD or DO):
1) Study hard and try to do as well as possible in med school.
2) Take Step 1 very seriously. A "good" score (and that's open to interpretation) will get you that many more interviews and will make your life easier. At least try to meet/beat the national average (USMLE=217, COMLEX=500)
3) Do electives in Psychiatry at the programs you may be interested in and put in 110% when you're there that month. I can't even begin to tell you how IMPORTANT this is!
4) If you want top programs, then a hint of research will probably help.
5) Personality (no pun intended.
) is very important in a field like Psychiatry. There's not much you can do about #5 at this point but I thought I'd put it out there for what it's worth!
G'luck in your decision, MD or DO.