The build is reasonable.
But, I think you can do better.
For gaming, the graphics card is all important.
My rule of thumb is to budget twice the cpu cost for the graphics card.
Here, you have a very nice $130 cpu and an ok $105 graphics card.
Look at this tom's $500 budget gaming build:
http://www.tomshardware.com/reviews/gaming-pc-overclocking-pc-building,3273.html
They used a G860 and a GTX560.
Prices and parts will have changed, but the budgets should still be good.
I might suggest a ivy bridge G2120 @$95 and a $160 7850 for example.
A single stick of ram will work OK.
But, a 2 x 2gb kit would give you dual channel operation.
Considering the low cost of ram today, I would try to get a 8gb kit of 2 x 4gb DDR3 1333 ram.
The Corsair builder series 500w psu is only $40 afer rebate:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139027
If you can, consider using a 120gb SSD instead of a small hard drive.
That will be large enough to hold the os and half a dozen games.
It will get you started and make everything you do feel so much quicker.
If you need more space for large files, you can add a hard drive later.
Intel and Samsung are having sales to deplete the inventory of 330 and 830 ssd's in anticipation of the new 20nm based 335 and 840 series. You should be able to find one for <$100. sales abound this time of year.
You get the idea.