Unless the 7 series comes soon, this next difficulty bump is pretty much going to make it impossible to break even on electricity.
Unless you mine with an old card or have massively high power costs, you must be stupid. Right now electricity is about $1.70 per BTC assuming 750w system, 565 Mhash/s (1btc/day) and energy costs of $.10/kWh. The difficulty would have to increase to about 4-5 million for it to be unprofitable to an existing dual 5830 miner.