It depends on what else you put in there. That is, how many disks, fans, lights, what CPU, whether you overclock, etc.
That PSU is an Earthwatts 500W with 2 rails of 17A each. That's pretty low for a GTX 260 IMO. Also, the Sonata doesn't have the appropriate cooling for such a card, I think.
I recommend you get yourself a RC-690 case and a 650TX PSU instead of the Sonata.