Need Recommendations on GPU Upgrade

Hey guyz/gals I would like to know what are some decent graphics cards for my system?

-Currently I'm running

-AMD Phenom II x2 560 BE
-M5A88TD-M /USB3
-Patriot G2 2x2GB DDR3 Ram
-Corsair CX 430W V2
-Sapphire HD 6570 DDR3
-Windows XP SP3 32 Bit

-I would need something that can run games on medium to high (does not have to be max) on a 1920x1080 Resolution and be able to run on my 430 watt psu.

-Must be under $150 since I am on a budget.

-Is it recommended to use Windows 7 since it utilizes Direct x11?

Thanks XD