I do a fair amount of flying with my laptop and, of course, always have to take the thing out of its cushy bag to go through security. The only scratches I ever got on my TiBook were from abuse in the airport security bins. I just ordered a Penryn MBP and want to protect it from scratches, since I think I will probably sell it within the next year or two to upgrade. So: would buying one of those hard shell cases (plastic skins) be a good idea? That way, the machine could come out of its bag and still be protected, but if the plastic shell will cause heat problems or something like that, then maybe it's not such a great idea. Does anyone have experience with these plastic skin cases?