I recently did a fresh install of Vista and applied all of the important updates. I then downloaded the latest drivers for my Canon MX700 that I've used for years over my home network with multiple computers.
The printing is now very slow from the new machine, and often jobs don't even finish. I also had a new XP install on another machine, and it now has the same problem.
Printing has continued at normal speed (fast) from my primary computer. Printing test pages indicates that the driver versions are actually the same, but something must be different.
The laptop that first exhibited the problem printed fine before Vista was rebuilt and the printer reinstalled.
When I ping the printer from the new machines, I'm seeing significant packet loss (about 20%).
I already tried turning off the firewall, and that didn't fix it.
I also updated the firmware on the printer to ensure that it was in sync with the latest driver download to no avail.
Make sure all computers are on the same work group. Go to start menu > right click My Computer (Computer in vista) > Properties, check the computer names are unique and that they are in the same work group.
Also make sure that guests have permission to use the printer. You can do this via your primary computer where your printer is plugged in.