Im not sure if it'll fit in that case... I put a 5770 in my dad's Storm Scout and it had plenty of room left, but 1, that case is a little smaller than the Sniper and 2, the 5770 is 2" shorter than the 480.
For $10 more, I'd go with the Cooler Master HAF 932. It's a full size case and will have more room than the Sniper.
http://www.newegg.com/Product/Product.aspx?Item=N82E16811119160
Im a big corsair PSU fan, the last 3 rigs Ive built, i put their psu's in em, including my dads and sisters... but for the money, I'd go with the Antec here, it's a little stronger and it's modular, which comes in handy, BIG TIME!
You're wanting to run 2 gtx 480's? Depending on what motherboard you're going to use, how many fans, hard drives, etc.. It's going to need around 800watts to power all that.
The kingwins, havent heard much about them but they get good reviews. If you can afford it, look at the corsair 1000watt.
Btw, what all are you wanting to do besides video card? What CPU are you wanting?