That seems like a good build, I would get an EVGA card if you go Nvidia and stick with corsair for the power supply. As far as ram, it probably won't make a difference but GSkill seems to be popular and reliable as well as corsair again. If you go with an aftermarket cooler for the cpu, everybody I know (including myself) has one of the cooler masters...they do a good job at a lower price. The case is going to be mostly cosmetic driven, but the Thermaltake Chaser MK-I I have has a lot of nice features like tool-less drive bays, dust filters, and even a slot for a bare drive on the top of the case (not saying to get exactly that one, but features to consider). Also remember if you don't get a full tower case (since you said you wanted to keep it smaller), make sure your video card will fit without issue as they can be pretty long.
I have a Razer Carcharias headset and a Plantronics Gamecom 780 headset. I bought the Plantronics one second because I wanted a USB set at the time, and have switched back to the Razer because the audio quality is much better and it seems to balance everything better...also the construction is great.