jjwillie,
in an internal pack you can tighten down the load to get it not to move much while hiking back to camp or down the mountain. the newer packs on the market that i mentioned earlier (badlands & eberlestock) are two great examples. Go to their websites and read over the packs.
one other item to help in getting your total weight down, is the pack itself. getting a good pack can save you a few lbs in weight.
http://www.badlandspacks.com/
http://www.eberlestock.com/