Beat my head against the wall so decided to post because I finally have it working.
Machine 1: Windows 7 64 bit
Machine 2: Windows Home Server WHS (or in your case any 32 bit Windows OS) with Canon Pixma MP780 printer
Can't install 64 bit drivers
on machine 2 (under additional drivers) such that machines on the network can connect to this shared printer.
Canon only provides 64 bit drivers for fax and scanner and not printer on their website because the assumption is that a native driver
is built into Windows 7 (64bit), which it is. The problem is that canon on both machines refers to this printer as two different names in the .inf file.
On the 32 bit side, it's called: "Canon MP780 Series Printer"
On the 64 bit native driver (that windows provides), it's called: "Canon Inkjet MP780 Series"
So, when I tried to connect to the network'd printer, it tried to look for it locally, on windows update and times out and fails (looking for the wrong name and therefore a mismatch).
Btw, I tried creating a local port on the 64 bit machine and gave it a UNC path to my WHS which works but after a reboot it doesn't so that's not "non techie" friendly and a pain in the neck.
Here's what I did:
Look for the driver under c:\windows\system32\driverstore\filerepository\<for your printer>.
In my case, for the Pixma MP780, it was : prnca00l.inf_amd64_neutral_4049bfb7d4c077ab
In this folder, the file was: prnca001.inf (setup information)
Try searching the contents of the file, maybe you can find it quicker (search for MP780 as an example).
Copy this entire folder to your desktop or somewhere you like (you will run into permission issues otherwise because this is a system protected folder).
Open prnca001.inf (used notepad but make sure when you save it, don't save it as a text file). Note that in my case the only one that I was concerned about was Pixma MP780 and therefore I changed it from "Canon Inkjet MP780 Series" to "Canon MP780 Series Printer"
Here's sample text I changed:
"Canon Inkjet PIXMA iP4000" = CANON_CNB_0220.GPD,CanoniP4000F4F6,Canon_Inkjet_PIXMA_iP4000 ; Hardware ID
"Canon Inkjet PIXMA iP4000R" = CANON_CNB_0235.GPD,CanoniP4000RBBF5,Canon_Inkjet_PIXMA_iP4000R ; Hardware ID
"Canon Inkjet MP750 Series" = CANON_CNB_0251.GPD,CanonMP750E1DC,Canon_Inkjet_MP750_Series ; Hardware ID
"Canon Inkjet MP760 Series" = CANON_CNB_0233.GPD,CanonMP76011DC,Canon_Inkjet_MP760_Series ; Hardware ID
"Canon MP780 Series Printer" = CANON_CNB_0250.GPD,CanonMP78071D8,Canon_Inkjet_MP780_Series ; Hardware ID
"Canon Inkjet PIXUS iP4100" = CANON_CNB_0221.GPD,CanoniP_4100ABA0,Canon_Inkjet_PIXUS_iP4100 ; Hardware ID
"Canon Inkjet PIXUS iP4100R" = CANON_CNB_0236.GPD,CanoniP_4100R872A,Canon_Inkjet_PIXUS_iP4100R ; Hardware ID
"Canon Inkjet MP790 Series" = CANON_CNB_0252.GPD,CanonMP790E1D9,Canon_Inkjet_MP790_Series ; Hardware ID
"Canon Inkjet MP770 Series" = CANON_CNB_0234.GPD,CanonMP77083DD,Canon_Inkjet_MP770_Series ; Hardware ID
"Canon Inkjet MP900 Series" = CANON_CNB_0243.GPD,CanonMP90072BE,Canon_Inkjet_MP900_Series ; Hardware ID
You're almost there!!!
Now, on your 64 bit PC, add a network printer, have it time out looking at windows update and so on and point/browse to the folder where your inf file is...it will complain that it's not verified, of course it ain't. Works like a charm and say, Canon, I ain't giving you another dime, you could have made my life easier.
I had to share this. Feel free to sticky it if you like.