It's a bit naive to think that hard work will get you anywhere you want to go. Just look at the NRMP match data - while DO USMLE scores have not been wholly accounted for into the NRMP trend data, DOs and FMGs have a higher chance of going unmatched compared to MD candidates with similar board scores. Board scores and clinical grades matter quite a bit, but there are also many factors that account for which residency programs will take you.
If you look at NRMP the average board scores for Independent applicants (FMGs and, maybe, DOs) matching ACGME residencies are actually lower than their MD counterparts for the same specialty (except for anesthesiology). However, I don't think those numbers apply to osteopathic medical students because I don't think NRMP receives USMLE data for DO applicants.
The reason why I think that is because
1): "Almost all of the applicants who did not have Step 1 scores were osteopathic medical school seniors and graduates who either take an alternative examination (the Comprehensive Osteopathic Medical Licensing Examination, or COMLEX-USA) or who take the USMLE exams but whose data are not shared with the AAMC."
2): If you look at the number of people that match with "unknown scores" and compare it to the number of DOs that matched, the numbers are about the same.
So, in 2009, for instance:
There were 169 people with unknown scores that matched EM and 171 DOs matched EM
There were 237 people with unknown scores that matched Fam medicine and 244 DOs matched Fam Medicine.
There were 32 people with unknown scores that matched Gen. Surgery and 31 DOs matched Gen. Surgery.
There were 108 people with unknown scores that matched Ob/gyn and 108 DOs matched Ob/gyn.
This holds true for every specialty.
So compare
http://www.nrmp.org/data/chartingoutcomes2009v3.pdf to
http://www.nrmp.org/data/resultsanddata2009.pdf if you want to see what your chances are.
By the way, what school you attend matters. If you go to a DO school and mess up, you are going to have limited options, and if you do great you are not going to have as many options as a MD counterpart. You will have plenty of options, however, so don't be too discouraged, but it is the truth.
I know a brother and sister that attended medical school at the same time. The brother was a DO and the sister was an MD. They both got the exact same board scores. They both applied to ACGME Gen Surgery. The sister got twice as many interviews and her interviews, in general, were at better programs. Some of their interviews were at the same places, however. They both ended up at university programs.