As long as you stay with the e6600, you should be ok.
If you move to a quad, then you do not have enough.
I currently run a Q9450 @ 3.4, with two 8800 GTX's in the loop. I had 2 x 120 rads, and all was fine with my e6750. Added the Q, and had to add a third radiator.
I was very suprised the Qaud pushed the temps up more and faster than the gpu's did.
Just be sure the fresh cooler water goes cpu-gpu-rad, and you should be ok. You might add a resevoir for more thermal capacity, which will help keep temps down.