There's a couple different sites that will allow you to estimate based on power consumption and price, and your hashrate (How fast you can mine, you can google each card to find out), how much money you can actually make mining. Unless you have a air conditioned room in your house dedicated to mining and relatively cheap electricity it probably won't be worth it. I heard some rumors about a guy out in Arizona who was using solar panels to power his bitcoin mining operation, pretty nifty if you ask me.