if you feel you are competitive enough for a JD/MBA program, then i personally don't think you would be a good fit for the schools that would accept a student right out of undergrad. speaking in general terms, the top business schools require some sort of meaningful full time work experience. smaller regional schools might accept you, but the resources available to you at these schools would not be the same as a top national b-school.
also i always put this disclaimer when someone mentions a JD/MBA (since i also thought about doing it at one point) - make sure you really really do some reading about the type of job prospects available to a JD/MBA. in theory it sounds like a great degree, but you really need to have a good understanding of what you'll do afterward in order to get some sort of benefit from it; otherwise, you're better off getting just one or the other.