In all honestly, you probably should not have got the second card. I had two 5770s and then two 6870s and I had nothing but trouble with them. Micro stutter is painfully obvious in just about everygame. I found myself disabling crossfire most of the time.
The more research I'm looking into now, the more I'm realizing the same thing - I really thought CrossfireX had come along more than I think it has....well, I suppose I could always just sell one of them off again. Thanks.