One of the very cool web sites I've come across in preparation for the expedition is called Maxpedition.com
It is chock full of cool back packs and such, like this versapack I picked up for day hikes.
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I also picked up this multi-purpose bag. Unfortunately my 17 inch lap top is a bit too big to fit in the side pockets; however, the quality over all is fantastic!
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If you are a hiker or back packer I definitely recommend them!
www.maxpedition.com