I have a Seasonic S12, powering a Q6600 and 4GB Corsair XMS2 800 ram, the cpu is clocked @ 3ghz. I fancy putting in http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=548066 I've my mind set on that beast of card, now is my Seasonic S12 600 enough, I remember the old power scary stories and I have heard some guys who run these and more on a 500watt Enermax but I feel better asking.
The power supply you have should be totally fine. Your CPU and the new card are each drawing somewhere around 130-140 watts, and if you add in another 30-40 watts for the motherboard and a few hard drives, you're still going to be using less than 325 watts.
