I think the power supply is more than enough. You could probably save some money going with a 750 or 850 watt unit instead unless you have plans to SLI down the road.
The antec 1200 cases has had very few innovations since the first one came out years ago.
I would recommend the Cooler Master Trooper which was released last month: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
The trooper looks absolutely awesome, it is a full size case, and it also has a handle on it for easy transportation.
Maybe able to trim some more money going with a EVGA GTX 570 also as the performance is no that far off from the GTX 580.
Well, it is always better to have too much than not enough. Per EVGA's website a single GTX 580 requires a 600 Watt Power Supply. However I can not find any listing for the SLI power requirement. I would guess it would be in the neighborhood of 700 to 750 watts. But I would get at least an additional 100 Watts on top of that just to error on the safe side.
However a machine of that caliber is a little outside of my expertise as I have never built something that ambitious. It would be better to take advice from someone on the forums who has a rig of that build. Or just play it super safe and go with 1000 Watt PSU.
Also you may want to check PSUs from Corsair and Antec. I think they would probably have a higher level of quality than Kingwin.
Slightly off the subject...
Hey, did you see the EVGA's new banner page? They just came out with the GTX 560ti 2WIN. Basically two GTX 560Tis SLI'd on a single card.