I wouldn't recommend building a mining rig right now, except if you want to use the components for computer games. If you factor in electricity costs and the increasing difficulty, it will take a long time until you break even. You will get about 10 BTC until the difficulty increases, after that you will get less (I'd guesstimate it to be about 30-40% every 2 weeks). So without electrity costs and a stable price of 16 USD per BTC you might be able to break even in 4 months.

I have to pay about 0,35 USD per kW/h (after converting it from my local currency). Your system will probably use about 800W, which would be about 200 USD for me in just one month. So with this rig I would lose about 50% of my BTC to the electricity bill in the first month, and even more in the following months due to the increasing difficulty.

So expect it to be at least 9 months (probably even more or never) with your rig running 24/7 until you might break even.