Yes, I downloaded and installed that huge file. When I run Image Zone or just use TWAIN access to the scanner, I get a message about important software routines being missing or corrupt. But they give no hint about what software that might be.
I have downloaded and installed from HP a 2.9 megabyte "Basic" driver as well. It runs OK from TWAIN, but does not support the slide scanning function.
Somewhere along the way (probably with the 2.9 Mby driver) is the message that they are "sorry", but that driver may not support some of the functions of the device.... Sure 'nuff, it doesn't support the slide scanning.
The "newer" machine runs XP Media Center. Since writing my initial plea, it has occurred to me that maybe there is a suitable driver on the Media Center XP installation CDs - which I have. I'll investigate that the next time I get to the system.