Same price as a CX600 and it is far better. And 280's require atleast 500w PSUs so this will definitely be good enough.
I have already bought the Corsair 600w About 10 days ago i was just triple checking to make sure it was compatible, but i got it when it was on sale for 39.99 and it also had a 10.00 rebate. In my next build ill be sure to buy one with at least a 80+ gold efficiency.
Okay sounds good. Efficiency isn't terrily important. Just the quality of the unit is what should be a concern. As long as you didn't pay more than 50 for the cx600 you're fine.