Next RAM, for a gaming PC there's really no reason to get more than 4 gigs, especially operating under what's going to be a tight budget when we fit in a monitor and OS. Also you'll have the ability to easily upgrade by adding 2 more sticks of RAM in the future to go up to 8 gigs.
At that point you're at 1274.50, so consider if thats where you want to be or if you'll want to upgrade parts, such as the monitor to a ~25inch LED for instance or add an SSD or upgrade from 560 to 570. You also might need to add thermal paste (Arctic Silver 5 will run ~$8 on Amazon) and keyboard and mouse to the budget.
I've got an extra minute so I wanted to add a bit of advice on taking my product selections.
A) Its difficult to search for good deals on RAM on Amazon because of the lack of filter features found on NewEgg/TD. More than any other item I suggested don't be married to that RAM.
B) I kept you a good $200 under budget, but if you have the money there are some upgrades out there to that system that you'll undoubtedly really enjoy that I suggested above. That said hopefully I've given you a good starting place when putting together a build.
Can I put 1 vote towards using the remaining budget towards a bigger/better screen. At the end of the day you have a high performance system there, you at least want to be seeing it in all it's glory on 24" minimum yeah? Your budget probably doesn't allow for Dell, but Asus or Samsung 24" 2ms 1080p is the way to go (27" if you can stretch) Many would argue for for the SSD... still a good option but you could always put one in later.