I'm similar to the above poster (step 1 under 220 and my school ain't top tier), and I think we're getting a little carried away...
Do programs prefer high board scores? Yes. Does a low board score alone prevent you from getting great interviews? No. All of the following will help your application/make up for a lower score:
strong clinical grades, previous/meaningful exposure to EM, meaningful research, significant volunteer work, saving the rainforest, etc. While having a higher board score will prevent you from being screened out, the two most important things (IMHO) to help you actually get interviews are EM rotation grades and the SLORs they yield. Not doing an away rotation or two will likely put you at a disadvantage. The whole application process is indeed random, but the idea that having more flair on you app will help you get more interviews isn't so far out there.
Oh, and here a few of my "top" invites: Denver, UNC, Michigan. Of course, I won't be at any of them next year--I cancelled all three. Everybody's definition of the "top" places is different, and for good reason (you know, different strokes for different folks). Two of my top programs right now are "lesser" name places that I think are amazing. Go wherever you think you'd be happiest. The end.