I use 4gb Kingston SD cards - not SDHC.
I've had zero problems with them and own a few of them for just this card.
I have a set of cards per camera type of mine and I never mismatch as their formats vary.
Mark the cards and only use them in that one camera.
I think I have about 15 cards in my pack for my 5 cams and they are all marked for which cam they're for.