try using a hammer and shorter nails with extra wide ends (make sure they are half inch longer than it is thick) the wider ends will keep the peg board from pulling off easily
I used 4" pieces of 1x2 at the top, middle, and bottom spaced every two studs - the less area your supports cover, the fewer places you won't be able to stick hooks. Rather than screws and washers, I was lazy and just grabbed the staple gun.
I have some photos in the article I submitted on organizing - hopefully it'll get posted soon. not sure you can see the supports in any of them though.