You must format an SD card prior to using it for storage. However, if you format the SD card into more than one partition, you can only use the active partition on the card. To delete partitions and ...
SDHC cards are cheap. I'd just get a spare 8GB one, toss it in the laptop bag and not worry about using a camera's SD card for such duties. I know it seems like it's a lot of space, but I'd rather ...