Update x86 Printer Driver

Alright, here's a new one for me.

I'm running Vista x64. I have a Canon USB printer that I am sharing,
generally with my laptop running Vista x86, but occasionally with other
computers running whatever version of Windows XP.

If I go to the Sharing tab in the properties of the printer, there is an
option to add additional drivers for computers running Windows on different
CPU architectures. I used this to install the x86 printer driver so that I
don't have to load it on each machine when it connects. Works great.

Here's the question. Recently, Canon posted a new driver for the printer
(actually for Vista, previously I had been using the XP and XP x64 drivers).
I can update the machine's x64 driver on the Advanced tab in the printer
properties, but I cannot figure out how to update the x86 driver. In the
"Additional Drivers" box, there doesn't seem to be any way to update or
remove drivers. Trying from the Advanced tab just gives a message that the
driver is not going to work with my CPU architecture. I tried deleting the
printer and letting Windows find it again, but it still had the x86 driver
loaded. I tried removing the x86 driver files from
C:\Windows\system32\spool\drivers, but it still thinks the driver is
installed.

It's not that big a deal, since the XP driver works fine in Vista, and I can
manually update the driver on the client machines if I feel like it. But,
does anyone know how to either update or remove a driver that is only used
for sharing?

Thanks! :-P

- Aaron