I also highly recommend Kalroth's version of cgminer! The xIntensity feature allowed me use 2 threads with my 7950, getting it to hash on par with my 7970!
http://k-dev.net/cgminer/You're getting over 700KH/s from a 7950?

Been running all night at 669KH/s, so close!
I'm using 4 as XIntensity (not the normal -I) and two threads with -g