Looking at http://www.dpreview.com/reviews/sigmasd10/page9.asp the hi-res SD10 files are about 8MB.

The jpegs (on the highest setting) that my Canon 10D produces are typically less than 2.5MB, the RAW file sizes on the Canon are lower as well, at around 7MB (though that has a hi-res jpeg embedded in it as well, so the actual RAW data is more like 4MB and if you choose to have a lower quality jpeg embedded the file is smaller).

I'm tempted. Haven't taken the plunge yet, got too much tied up in my old kit 2 x OM4Ti + lenses from 16mm fisheye all the way up. Now if I'd got rid of my Olympus stuff instead of all my EOS stuff I'd only have to buy a body...