I am currently building my own personal computer for gaming purposes. My plan is to have capable of handling guild wars 2 when it is released this summer. I am on a budget so I can't switch too much (around $700). Also, I already have a 1900X1200 23" Monitor, Keyboard, and Mouse for it.
You need to use Win 7 64-bit with that much RAM (32-bit can only address 4GB total including the RAM on your video card).
Other than that it looks solid. Keep an eye on GPU prices as they are still in flux from the introduction of the 680 GTX - you may be able to get more bang for your buck.
One other thing to consider is Ivy Bridge is only 19 days away and looks to be just slightly more powerful with less power usage at the same price point (and Z77 mobos may be slighly less than Z68s due to needing less 3rd party controllers). Just a thought.