It depends on how that 500W total is achieved.
Most of the cheaper / older PSUs don't allow much of the stated power over the 12v rail(s), which is what most of the components in your system run from.
Check the sticker on the side of the PSU and see where the power if available.
For a mainstream CPU (<95W TDP)and a 570 you'd be wanting about 450W on the 12V rail, which is 37.5a.
If it's a cheap PSU that came with the case, I wouldn't risk it. Such things are rarely able to achieve the power they say they can except @ 15 degrees or something silly.
If money's tight, it might be an idea to drop to a 560Ti and get a new PSU like
http://www.aria.co.uk/SuperSpecials...US+Gold+Modular+Power+Supply+?productId=41315
May seem pricey but a decent PSU will last and give you peace of mind that it won't just blow up and take £1000 worth of computer stuff with it