or am i looking at doing the memory and cpu too?
Nope. The CPU and the RAM are perfectly fine for now.
When you run things at 1080p (1900x1080) you don't need AA set as high to have smooth edges. Try using just 2x or maybe none at all. That should improve performance a bit without really impacting quality. I run a similar setup w/ a lower clocked CPU and still get a steady 50-75FPS from CS:S at 1900x1200 (All settings High, 8xAF, 2xAA)
just noticed some chaps overclocking gpu's so maybe try that to tie me over.
I've got the same GPU and I've been considering the same thing.