I have a Navigon 5100 GPS device that takes SD cards. It comes with a 2GB card but supports 4GB cards. I bought both a 4GB SD (non HC) card and a 4GB SDHC card. The Navigon can read the full 4GB on the SDHC card but only the first 2GB of the non-HC card. That was true even when I formatted the non-HC card as FAT32. So there must be a difference in the addressing scheme between HC and non-HC cards for addressing the memory above the first 2GB.