The 800mb of Compact Flash memory comes in handy when shooting with the 4mp Canon G2. I have easily filled up a few cards in an afternoon of shooting. The Sony MemoryStick is from a Digital 8 camcorder. The 64mb SD (Secure Digital) memory card is from the SanDisk Cruzer, a portable data transport device. It works like the old USB memory key (connects to a USB port) but is completely expandable. I find the Cruzer is invaluable for transferring data to and from home desktop,laptop and work PC.