I have a MacBook arriving today from Apple and I'm starting to get excited about it. I was wondering -- is there any benefit in formatting the drive and installing the OS from scratch over just using whatever Apple put on there originally? I usually have done this with new machines just to make sure the drive has no errors and everything's installed correctly, but it is time consuming and perhaps unnecessary. Thought I'd ask what other people do. Oh, this is a refurb, too. Not sure if that matters. Thanks!