Hi I have the Canon 20D and loving it, btw. I did get the 1 gig Compact Flash Card. With a 1 gig, at full scale photos.. taking pics with it's highest resolution of 8.2 mpx, you will have at least 220 shots! Well that's what I got, havent tried the microdrive. This is what I've found in most discussions between comparing the two:
comparison
Alright.. I hope you have un taking pics! Please share them with us as well! Have a good day!