The main reason for me getting into mining is to try and make a small profit from my unused hardware now that I'm not paying for electricity in my new duplex.
Those cards might do maybe, combined, 0.85 Ghash/s. If you plugged them in today and difficulty were to stay the same, you'ld get about 14 bitcoins between now and "halving day" (occurs at block 210,000 -- less than 50 days away). That's worth about $150 (using today's exchange rate). The electricity consumed to get that is probably close to $100 worth, if you were to pay anywhere near normal residential rates (e.g., $0.12 per kWh). You'll probably be putting in more than ten hours of work for this though.
After halving day, assuming difficulty stays the same (it won't once ASICs ship) and the exchange rate stays the same (it likely won't, but nobody knows which direction), that set of hardware will earn about $45 per month.
If you were paying directly for the electricity, that would burn about $60 worth of electricity.
And that is why people are not recommending you start mining with GPUs today, because it will be cheaper to get bitcoins by powering down your GPUs and using the money you would pay to the electric company to instead buy BTCs with cash at 7-11. In your case, your landlord is subsidizing your hobby and you get to keep the $45 worth of bitcoins.
