I constantly transport my 13" white MB while it's turned on. That is, I close the lid, put it inside its neoprene sleeve and into my backpack...to be lugged around for the rest of the day. Is this safe? Can it suffer from HD failure at some time? I was under the impression that once the lid is closed the computers goes to sleep and nothing "spins" any more...so what damage can occur, right? Well, a friend just had to replace the HD on his MB and the tech guy said that it was damaged because he never turned it off before moving it around. Can I keep doing this and be on the safe side? Should I shut it off before transporting it? I use my computer while visiting clients, so powering down and then turning it on for every visit I make is not only bothersome but most of the time impractical because I can't sit in my clients office and wait till the computer shuts off before leaving...you get the idea. What's the final word on this?