Your video card alone is asking for a 450w psu. I would suggest more than a 50 spare watt buffer for everything else you have to power. I built my first PC last month with a very similar setup, same cpu and gpu. My video card asked for at least 500w so i got a 650w psu. Nothing wrong with a little extra leg room. You can find a 600w - 700w for around the same price. That's the route I would take, then again.... I built my first pc last month.
zotac draws 330 at load see link below. 500w should be fine but if you have a little more cash I'd get something a little higher for better efficency as running close to full power on PSU is less efficent than running at 80%