smb4k is working fine so presumably Samba is Ok
I had the very same printer plugged into my PCLOS machine as well as a Fedora laptop I was playing with. In both cases CUPS recognised the printer and the printer worked fine with jobs from my PCLOS machine.
PCLOS print job to directly attached printer - OK
PCLOS print job to networked printer on Fedora laptop - OK
virtualised XP (under PCLOS) print job to networked printer on XP laptop - OK
PCLOS print job to networked printer on XP laptop - Does not recognise printer.
From all that's working all the pieces of the puzzle are in place, cups, samba, canon drivers, ports, XP serving Linux on, etc etc. So why that last failure?