One other thing which I can't believe I forgot to mention - I can't recommend trekking poles strongly enough for your knees. I used to have major knee soreness. I started using poles and I can't overstate the positive difference they make. They are readily collapsable for sections where they are not helpful. You can get a pair of the cheap Wal-Mart jobs for 20-30 and they're very sturdy.
You can do a quick Google search on them if you are not convinced and there are several places that give a numerical breakdown of the cumulative force removed from your knees per mile.
"Use what talents you possess: the woods would be very silent if no birds sang there except those that sang best." —Henry Van Dyke