Re: A few general questions
You'd only need to put one of the video cards in I don't think the 5770 and 3850 are crossfire compatible. They have to be from the same series to be crossfired soo both 57xx or 38xx. I'd throw the 3850 in there and shelf the 5770 until you get the new computer build. Then Put the 5770 in the new computer.
i7-930 currently no OC, 6 gigs Corsair, Gigabyte GA-X58A-UD3R Motherboard, Asus 5770 HD gpu. Running like a dream.