Merlin, congrats on the well-deserved press! I'm another convert, thanks to your site. I have a huge array of PDAs because I used to work on them. (Anyone remember General Magic?) I've got a dozen or so Magic Cap, Palm, and Newton gizmos in my basement. Even when I lived and breathed PDA development, though, I never used them consistently. Pen and paper is always the path of least resistance, and I always fall back to it.

The great thing about 3x5 cards over notebooks is that you can quickly re-sort them to always keep what you need easily at hand. I'd sometimes lose to-dos in my notebook because my current writing was several pages ahead, but that problem goes away with cards.