I had a problem, with the Epson TX600FW multifunction printer/scanner/fax (connected via wifi network), the printer would work with the latest vista driver
from the manufacturer's website, the scanner would not, the Epson Scan software would install without errors but would not run, even in compatibility mode.
Windows scan/fax software, and any other programs I tried could not detect the scanner. The install CD that came with the printer wouldn't install. The printer wasn't showing up under device manager.
In the end I copied everything off the install CD to a folder on my desktop and ran the main installer in vista compatibility mode. Installed everything perfectly with no errors, and everything is working great now.