Unless I'm mistaken, compatibility is as follows:
2 GB or Less - Non-SDHC
More than 2 GB and Up to 32 GB - SDHC (Gecko Code REQUIRED for SDHC)
Do they even make 2 GB SDHC Cards, or Non-SDHC cards that are larger in size? I don't even think they do, except for possibly 4 GB, and even that, I dunno if they make 'em for that; also,
this guy sent me some information about the code, so I would highly recommend contacting him for more info on it