Any chance you bought one of the newer and/or larger "SDHC" cards (iirc, they are the ones that are larger than 2GB) Not sure if the SD cards under 2GB are made in both standard SD and SDHC or not, but the SDHC cards are physically identical to the SD cards, and there is really nothing from a geek perspective that makes them different, but they have a "flag" that identifies them as the SDHC variety and the standard SD interface of card readers and cameras (those not equipped for use of SDHC cards) will not recognize them. There is a software update for WindowsXP that will get a standard SD reader to recognize the SDHC cards, but I am not aware of any manufacturers who have patched cameras with older readers, or if it is even possible.