Xeos :
Any cases in mind, I only picked that as it came with the PSU.
Oh I( missed that it has a PSU too. But still you may want to get separate Cabin and PSU because I dont know abt the reliability of the PSU that is in that cabin u selected.
Here is a good cheap PSU with 80+ bronze
http://pcpartpicker.com/part/evga-power-supply-100b10500kr
And u can choose any 50-60 buck cabin that u like because looks is more of a personal choice.
Try getting the r9 270x in place of the 660. You will get a performance boost. You can get the fx 6300 that will save you about 25$ that you can invest in GPU. All I want to say is that u are making a game machine, you need a good gpu!! 6 cores @ 3.5ghz from cpu side is enough.