I got an asrock p55 extreme mobo with my recent build to find I overlooked that the hd 5770 is not supported in crossfire on this board. Is it likely support for this video card will come in time or would I be better of finding a mobo that supports the cards I have?
I don't see why this board would not support crossfire on the 5770. It's a CrossFire compatible board, so as long as your video card is Crossfire capable (which the 5770 most certainly is) it should be completely fine.
The biggest question is whether your power supply will power two 5770's or not.