well ur dual core is at 2.8ghz and most modern games run better with a higher clock speed and at least a quad core. issue is a x4 965be is a 125watt cpu, which most likely ur board wont take, but a 1045t x6 is a 95watt cpu has triple the cores u currently have but only a 2.7ghz cpu, but would run great with a 7770/7870. The 7770 is about $120, which gives u room for a new cpu like a 1045t or a 95watt x4, and a new power supply like a corsair cx430
U can readily get a 1045t at tigerdirect for $100, or a athlon ii x4 640 for $80, and newegg has a msi R7770 for $120, and and cx 430 for $45