Hi, Peter et al:
Just to confirm, all current EOS digitals can be used with high-capacity CF cards (above 2GB). As of January 2006, the SD Card Organization had not yet ratified a standard for SD cards with capacities higher than 2GB. They issued a press release confirming that fact, and announcing that they were working on anew standard to be called SDHC, for "SD High Capacity." The good news is that the SDHC standard has finally been ratified, and we are expecting firmware updates for all Mark II EOS digital SLRs over the next few months. The potentially bad news is that at least some of the currently available 4GB SD cards may not meet SDHC standards. If you have any questions on this, I would suggest that you contact the card manufacturer or distributor. In the meantime, the Mark II cameras currently cannot format high-capacity SD cards in camera, although many users report successful results formatting such cards with their computers.
Best Regards,
Chuck Westfall
Director/Media & Customer Relationship
Camera Marketing Group/Canon U.S.A., Inc.