pdterp's solution works for me. I have a desktop server - WinXP 32 bit with the Canon MP780 attached - called desktopgw.
I installed the latest drivers on the XP machine and set it up to SHARE - NOTE the share name - mine is called CanonMP7.
On my laptop - Dell M6500 Win7 64bit - I added a printer, adding a new local port - called \\desktopgw\CanonMP7
Rendering print jobs on Client computers (under sharing on the Win7 machine) was automatically checked for me.
Works like a charm - it even downloaded the right drivers for me. I never had to manually install any Canon drivers on my Win7 machine.