I'm loving my new macbook right now but... when I put it in the padded laptop sleeve in my backpack, it's way too small and it "floats" around inside (the backpack is made for a 15.4", much thicker laptop). Even the MBP doesn't fit snug. The end result is that when I walk around, the macbook bounces around a lot (especially back and forth...I can feel it hitting my back) I know this can't be good for it. So...what do I do? The first idea is to get some foam, but I'm not completely sure how to make it work...just cram it in there?