I'm using noob-friendly Bitminter on a Mac -- one USB as an experiment -- and getting 0.0087 BTC / 24h.
Thats about dead on. Will take years for ROI. But oh well.
Please take this as a face value question: Have you ever studied discrete mathematics?
No, should I say. "You'll never get ROI?" I believe BTC will go way up in price. Therefore ROI is possible.