Before buying my new PC with Vista installed I did the compatibility check
which told me that my Panasonic KX-P7100 would work with Vista.
To my disappointment it didn't, XP computers networked through my PC could
use it but my Vista couldn't and Panasonic are not releasing Vista drivers
for that model.
As a last resort I dug around and found an old printer cable, uninstalled
the USB drivers and then reinstalled it using the Add a local printer
routine in the Printers folder, to LPT1.
YEAY, it works perfectly, the other PC's on my network can also use it and
it has retained all of its functions, including Duplex printing.
I post this message in case someone else is struggling with the same problem.