The first folder that the camera creates on the CF card is numbered 100, the first image is numbered 1 - which adds up to a file number of IMG_0101 - and every 100 pictures, a new folder is created on the card.

Also Canon has repeatedtly confirmed that due to in-factory testing before shipment the number can be larger than that in case they didn't reset the file numbers after testing.

Of course, you can't always rule out that a sales rep in the store has taken the camera out and done some test shots before selling it, however, if the camera appears new and okay, I wouldn't worry about this at all.

(nubui)

"The most likely case is that the user inserted a used CF card from another Canon camera into the 300D. The camera will continue to use the file number existed on the CF card and synchronize the internal file number counter to that. I use this technique to transfer one CF card between my G3 and 300D."

Thanks for the input!

(nubui)