Yesterday, as I carried my dying 13-in MacBook Pro to the Apple Store, I was reminded just how heavy it is in comparison with the 11-in MacBook Air I’ve been happily schlepping around for the past six months. This was the first outing for the 13-incher in all those months and I had to fish out my old (and heavy) Crumpler messenger bag to accommodate it. It felt like a ton on my shoulder, and I can’t imagine how I ever managed to carry a 15in laptop, or, dare I say, the 17in MacBook Pro I owned for a season back in 2006. The Air is so light you can forget about it; it’s hardly heavier than the new MacBook Pro in real terms. Now, of course, I face the daily decision whether to take the Air or the iPad. Things were simple before the iPad came along.