Dave this is well documented. You can use
the 4GB SD in the Mark II cameras, but you cannot format it in the camera
. Format it in the computer instead.
If you have a problem formatting in computer due to the failed attempt to format in camera let me know. There's a fix.
Thanks Nill. I formatted in the PC, and took two trial shots with the camera. It did indeed work. But when I put the card into my card reader, and tried to use the Canon File Viewing utility, it did not find the card. Don't know if its a software issue (Canon Utility), or card reader problem.