First question, why the hell would you use ATI? That **** is garbageware... Go nVidia dude, don't let these noobz tell you ATI, that **** is too funny.
I like OCZ memory better than G. Skill, but that's a matter of preference i suppose. I use the Antec Quattro 1000 PSU. Me mate has had bad expierences with Corsair psu.
I had a Thermaltake Shark case, it was ok, but I love the Antec 1200 so much better. That case is the ****!
How do you feel about a mobo with onboard wifi?
I agree with the other guys about sticking with the onboard sound. Check it out and see if you like it first. I high end board will have nice digital sound supporting 7.1 and some nice connections, like S/PDIF.
I think you're spot on with your CPU, that's such a dope ass one! At least you didn't go AMD...
Best of luck on your build.