CPU mining is ludicrous, it would take you a year mining 24/7 on a new i5 CPU to even make enough Bitcoin to meet the minimum withdraw amount on pools, while costing ten times more in electricity than your earnings.
http://we.lovebitco.in/mining/
Anyone else care to take a stab at this explanation? I don't think I did it justice.
http://we.lovebitco.in/mining/
So you are saying that 8 i5s could do the same job in 1.5 months. Granted. i5s us a lot of power, probably more than you could make in coins. But Atom processors are relatively cheap and low power. Granted they are slower as well.