I just moved blogs, so here's an overview of the SD card CID stuff. I've had some success reading the CID from an SD Card: Where: 1) The OS is XP or Vista 2) The device is not attached via any USB gizmo. It works only in a card reader attached directly to the PCI bus. (Can scsi pass through get around this? It's not an ATA or SCSI command...) 3) Admin privileges... What not to do: 1) IOCTL_DISK_GE