Hi James,
Check out the free ExifTool. It just released a new version on Dec 15 including a standalone executable for windows (this program also works under linux and, I'm sure, macs as well). It reads/write canon raw format images.
Here are some user comments about the program
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"In my experience, nothing but nothing is as complete, powerful, and flexible as Phil Harvey's exiftool ... I've never seen anything that's in the same ballpark for power." - dpreview forum
"While there are a lot of image tools available, nothing comes close for accessing/updating the metadata like ExifTool" - merg's blog
"exiftool is an amazingly powerful Perl module and script" - Brett's Place on the Web
"Fast, reliable and amazingly comprehensive ..." - CPAN ratings
"... the one piece of free software that gets the most detailed exif data of /any/ tool I've found." - gnome mail archives
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Good luck!
Bart