Help buying a new gaming pc.

if you want to play games you should get a better video card as 7750 is minimum

It will certianly work. Your board supports 1600 speed DDR3 when overclocked. I would consider over clocking your memory and buying 1600 sticks.

I would also consider spending the extra $35 for a 7770.

It will run a majority of games at a low setting, at least modern games. Older games it would do much better at. It will depend on requirements. I do have a few suggestions.

1) If you can upgrade to an FX-6300 you would be much better off. You are getting the newer architecture and more cores. In the US that is about a $35 upgrade and well worth it.
2) I'd get DDR3 1600 RAM, it is usually only a couple bucks more. If not, it probably won't make much of a difference.
3) You do not need 500W for that system. The 7750 could run off a good 380W power supply. You can look at a 400-450W good PSU and use that money for a better card. Maybe a 7770 or GTX 650Ti.

The above changes will all depend on your budget. However, sometimes a slightly higher budget will yield you quite a bit more performance.