Even with an efficient ATI GPU, at current difficulty, current BTC/$ exchange rates, and your electricity rates, you will be losing about 1/3 of your mining profits to pay for electricity. You will likely not be able to break even on any GPU investment prior to the block reward reduction in December (when the block reward will be cut in half from 50 BTC to 25 BTC).
I don't understand, did you mistype? You said I wont be able to break even prior to the block reward reduction, doesn't this reduction mean that one would be earning less per block?