I've never had problems with SanDisk or Lexar CF cards or IBM Microdrives. As for speed, I don't really notice it. 10D has a 9 photo buffer so I probably wouldn't notice even the slowest cards. As for which format to shoot in, I think the best description of the difference between JPEG and RAW I've heard went something like this: Shooting in RAW mode is like shooting with film and when you're all done you get back negatives to make your photos with. Shooting in JPEG is like shooting with film and when you're all done you throw the negatives away and just keep the prints. RAW is the digital equivalent of a negative. Everything your camera recorded when you took the picture is there. You now control how that is brought forth. You can change exposure, white balance, contrast, tint, etc. You also do it on the pristine data giving you the best quality. The downside is that you are now responsible for everything. Sort of like being a photographer with your own darkroom. Also, RAW files are usually 2-4 times larger than the JPEG equivalent. -=>Donald