Right now I have a messenger bag, which is decently sized but not that large. I'm getting a 15" MBP very soon and want to be able to carry it around. However Im currently in college and thus I will need to carry a couple other things at a time, maybe 1 book and a notebook along with the mbp. So should I pick up a new bag -- I would only want a messenger bag, not a backpack -- or find some kind of sleeve that i could place the mbp in which i could then place in my bag I already own. In either case, I want to make sure that the MBP stays very safe. could you recommend either a particular brand/model of sleeveo or protective case (assuming i keep my old bag) or a new messenger bag that would fit my criteria?