It seems that my Powerbook was more reliable than my MBP. I would not trade back for it, I like this one, but it doesn't sleep well. Especially since 10.4.8. Sometimes I close it and the screen turns off, but it doesn't sleep, and a few hours later I come back and the battery is dead and it's hot. I don't recall ever having these problems on my PPC. I'm curious what it's like for others.