Hi Guy!
I'm using a couple of 512Mb CF cards with my 10D, each card gives me 203 shots on fine JPEG or 80 shots on RAW.
Never had a problem with capacity yet.
HTH.
I love our camera, we've had it about a year. We have 3 512 cards and a couple of 96 left over from our first digital camera. I always make sure to have several back ups just in case something happens to one of the cards.