Don't bother upgrading the graphics card unless you can afford another processor and motherboard as well. You current APU is awful and literally slower than the cheapest Celeron, and will bottleneck whatever graphics card you put in. I'd get a Pentium G3258 and a cheap MSI/ASUS/ASRock motherboard if I were you, and preferrably a GTX750. Also, don't listen to Bisjac's power supply advice, he doesn't know what he's talking about. An overclocked G3258 and a PCI-e only 750 will never use more than 250 watts at full load, and probably less than 150 when gaming. Unless your current PSU is proprietary, low-quality or very old there's really no need to replace it ASAP.
I'm currently away, but give me a budget and what parts you already have and I'll put together a build for you when I get home.