I think its hard to make a blanket statement about this as it varies from program to program. I applied to a local, in-state program that bases acceptances and rejections completely on pre-req GPA and GRE scores (they told me this) and was rejected. However, I applied to the #1 program in the country and was accepted as they look more at the overall resume of the candidate. If I had to pick the 2 most important categories (to the school, that is) I'd say pre-req GPA and experience.