So, I have an 8,1 24" iMac (Early 2008) and leave the power applied almost all the time. I do this because it takes forever to boot ML. The bad thing is that it tends to freeze up a lot when I do this. I am patiently waiting for my Late 2012 iMac 27", 3.4GHz, 1TB/Fusion, 680MX (still processing) and wonder if I will have the same need to leave it powered on. Do you guys leave your machine on? And for what purposes?