You are totally correct Denis. I was a tad bit hasty in my answer. It should be: C(13,2)*C(4,2)*C(4,2)/C(52,4) where C(13,2) is the number of possible differing pairs and C(4,2) is the number of possible pairs for the denomination.
Sometimes lost is where you need to be. Just because you don't know your direction doesn't mean you don't have one.