old WinXP driver not recognized by up-to-date XP

I have a Canon DR2080c scanner with a SCSI interface. I'd like to run
it with a Windows XP system. Canon makes a driver package available
on their web site that claims it works with Windows 95, 98, ME, NT4,
2000, and XP <http://www.usa.canon.com/opd/controller?
act=OPDSoftwareAct&fcategoryid=2341&modelid=512>

My XP system sees the scanner and asks to install a driver.
Unfortunately, when I give it the unzipped package, it does not
recognize it as a driver.

Why would this be? Has XP changed to rules since 2003 (when the
driver was packaged)?

(In a separate download here is a .inf file for Win2000 and earlier.
The XP installer accepted it but it didn't seem to do anything: the
hardware config still had a ? next to the scanner.)