Thanks for the response.
I went ahead and deleted all the folders in Library/Printers, since I only want one Canon driver and not all the other bloat.
I then downloaded Gutenprint 5.2.6-rc1 and installed those drivers.
I then installed the Canon Gutenprint iP6000D 5.2.6-rc1 printer.
Same result. Anything printed has a slight monochroming effect to skin tones, kind of like a light sepia filter being applied to everything. I tested printing a web page in Safari as well as a photo in Aperture, and the results are the same, regardless of which Color Profile I choose. I tried Color Profiles of 'Printer Managed', 'Photoshop 5 CMYK', and 'Generic CMYK' and as far as I can tell, changing the Color Profiles makes no difference in the print.
I'd rather not unhook the printer from the PC, as I'd like to be able to print to this Windows 7 attached printer. Certainly there has to be a way to use the Canon 'OEM' driver to print to this networked printer? I am really frustrated over this whole situation. I thought Macs were supposed to 'just work'. Even printing from a $200 cheap netbook yields excellent printing results. I don't understand why this is so difficult. At present, I don't dare try to print any type of photo from my brand new top-of-the-line $2500 Macbook Pro. Ridiculous!
Thanks for any help you can offer on resolving this increasingly frustrating issue.