Maybe I spoke too fast. While the Lite-on works in pio mode, it does some strange things when reading. I made two DVDs of images for backup before I upgraded to XP. Now the Lite-On reads and transfers both DVDs to new folders, but one of the DVDs files cannot be read by Photoshop, while the other DVDs transferred files can! I made the backups one after the other, one the same media.
The other drive, a Toshiba DVDRom, reads both DVD backups, and files transferred from the Toshiba are all read by Photoshop!
I'm getting weary trying to figure all this out. A couple of more hours and I'm going back to Win2000, where everything worked.