if this is a family/general purpose pc, then a gtx 460 would be more than enough. as your case, pick something a little more friendly oriented, yah? something like a simple coolermaster 590 should suffice.
I need to save up another 2 or 3 months to buy the graphics card, by then the prices of hd6850 and gtx 460 will have dropped at least a little bit.
Here is a pic of the motherboard, I really like the design: