That does not include the OS, neither does it inclue the Optical drive.
Your CPU will probably OC to 4.0 Ghz on the stock cooler. Asus enabled overclocking on their H81 motherboards, so no problems there. Its from newegg, so its bios is probably up to date. You can add anohter stick of RAM later. You also can add some fans later. However, your GPU will be bottlenecked a little until you OC.
That build should give you very respectable framerates on most games. BF4 multiplayer may lag a bit. I suppose its going to handle assassins creed 4 on high.