I really hate recommending cases based on aesthetics, since people's tastes vary so much.
I would simply recommend googling for computer case reviews and see what you like (and has a good review). Some popular cases recommended here are the Antec Illusion 300 (which I believe is on sale right now) and the HAF 922. I don't particularly like the looks of either of them, but they're apparently well-designed mid-tower cases. I actually think the HAF series is ugly as sin, but lots of people like it.
Try out the Antec 902, perfect size, great airflow, asthetics are pretty nice, plus it has cable management holes.
The XFX 750 is a great choice BTW.
Umm I don't think that's a very great gpu choice though. Mainly the model. From what I heard, the Toxic was disappointment even the first released Sapphire cooled better/on par to it's Toxic counter part. Might I suggest one of the best gpu heatsink cards. The Asus DirectCu 6850. http://www.newegg.com/Product/Product.aspx?Item=N82E168...