just tested it using picasa (I never installed the Canon software, and wonder if I'd missed anything) and apparently CRW and CR2 works (not THM, DNG, didn't try WAV.. and .jpg would just be too confusing). There's still a checkmark at the bottom at "DNG format". I suppose it's just the compression method irrespective of the extension?
Thanks for the information. I think the only reason for me to try to avoid using the cardreader was that I had to flip the write-lock switch every time I download, or else I have to go back to the camera to erase it, an extra step; where if I use USB the files on camera can be erased using the software. Also plugging a wire seemed "cleaner" with less "wear and tear" than having to open AND close doors while the card is loaded (and open again to put the card back in), having to fidget around the lock switch, etc. etc..
Anyway, thanks for your help. It's much appreciated.