Good morning! I am a new MBP owner and a student. I am looking for a backpack that will keep my computer safe and doesn't look so much like a laptop bag. After looking at many bags online I think I have decided on the Timbuck 2 "Underground". Looking at thier site, they claim some bags are made to fit the MBP and others for "15 or "17 Powerbook. Is there that much dimensional diffrence between these two machines? I plan to buy a sleeve for a little added protection but I dont want the computer to move around too much. Does anyone that hass owned both of these machines think I will be ok with this bag for my new MBP?