I just spent about an hour figuring this out, so I thought I'd put it out there, as much as a note to self as maybe to help others having the same problem.
I wanted to print from my work laptop running Windows Vista (eeewwww!!)
to the printer that is connected to my Mac Pro running Mac OS X Leopard
(10.5). I did all the obvious stuff. Enabled printer sharing on the
Mac, added a new printer on the laptop, which succesfully found my
printer. Click next, couldn't find the correct driver, so downloaded
Windows driver from the manufactur's website. Clicked "Have disk",
pointed the installer to the downloaded driver, all good so far. At the
end, try to print a test page. Nothing.
Some Googling told me that I should not have selected the driver
corresponding to my printer, but that Mac OS exposes all printers as
PostScript printers. Aha! Next problem: what driver should I then
select? All the suggestions I found on the net, such as Apple
LaserWriter, were not available on my Vista installation. One result
did nudge me in the right direction: the "Generic" manufacturer in the
list of printer models. However, the specific model mentioned wasn't
listed. So I picked one that seemed remotely likely. It worked! Test
page printed, happy happy, joy joy.
Long story short? When selecting a driver on Windows Vista for the printer connected to your Mac, pick model MS Publisher Color Printer from manufacturer Generic. YMMV, of course. For the record, the printer I am using is a Canon MP610.