jan--
i thought i wanted to go this route and did some major researching..
rockndoc is right about the paths..
if you are a DO, the only DO combined program is at chicago college of osteopathic medicine..it is good b/c it is totally through University of Illinois at Chicago--an allopathic program..it is bad in that I feel the peds department at CCOM is fairly week, it is breaking up b/c many of the faculty are leaving, and there is not a big census when you have to do things at the core CCOM hospital..but the training at UIC is through their hospitals, including Christ which is just an incredible training program.
keep in mind that if you are doing a combined, you cannot moonlight until basically you are finished b/c you cannot sit for the boards at the end of your 2nd/3rd yr b/c you will be on an alternating schedule.
also keep in mind that these fellowships are competative and are few and far between.
if ER is what you are really interested in, and peds is a big interest but you don;t see yourself spending the rest of your life in an office peds setting at any time, just go straight ER.. in a county setting in particular, you are going to see wads of peds..
good luck!