None of the Canon drivers, even the latest versions, can be used when you want to connect via a Windows share. This is due to a limitation in the Canon. It was the case with previous versions of OS X and is still the case with 10.6.
When you have the printer shared from Windows, you need to use a CUPS based driver, such as those offered by Gutenprint or
PrintFab.
Gutenprint is the preferred choice, because it is free. However not every model of Canon is supported with Gutenprint (such as the iP1500) so this is why you sometimes need to purchase PrintFab, which does list the iP1500 as a supported model.
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