Windows7 access to printer shared with XP?

The solution was to install a 64bit version of the driver on the XP computer. I downloaded the 64bit Canon driver for Vista from the Canon web site and uncompressed it on the XP computer. In the printer properties, there is a button below allowing to specify alternate drivers for other type of computers. I checked x64 at the bottom of the list. A dialog opens requesting to give the path to the .INF file. I found my way into the uncompressed driver folder to the 64bit version which was accepted and installed on XP. The W7 computer was then able to download the driver and could print the test page.

With this configuration, all PC (XP,Vista,W7) can see and use the printer. The eeeBox on which it is connected is used as a small printer server.