5750 is ok too, but then you need a new PSU. If you don't really mind about quality the go for older NVIDIA, for example, 9500 or 9800. I'm quite sure for the 9500 your power supply would be sufficient. It can play most game at almost the max settings, (low AA though, and no DX11). It's surprising to see such old hardware can still keep up with current game.
What's your monitor resolution by the way?
But if you have money yo spare, I suggest you upgrade to a better PSU and 5750 (or above). Oh I recommend Sapphire 5750 Vapor X, that's what I am using.