A good quality 550w PSU would be quite sufficient for you rig.
SeaSonic M12II 520W - 80 PLUS BRONZE Certified Modular Active PFC Power Supply http://www.newegg.com/Product/Prod
XFX Core Edition PRO550Whttp://www.newegg.com/Product/Product.aspx?Item=N82E16817207013
Btw, Which CPU? is it overclocked? are you planning to OC your 570? Is there any plans to run dual 570 in SLI ?