What am I missing to build my PC? And whats a good Video Card to add?

its a perfect gaming system if you want to use onboard sound and from my memory the onboard sound of your mobo is 7.1 so that should do. for your graphics card it depends on where you buy, you can either get the 8800, ati 3870, ati 4870, nvidia 260, nvidia 9800. check the place you're buying from for the prices.