Yes, Vista really was that bad. It's not as bad as Windows ME but it sure was a fish out of water. It might have had more importance if XP would have been discontinued sooner. I don't know of any enterprise that is using Vista but there are more and more moving to 7.
Are we talking about a file that we have copied to a different media? ex. a copy of a file on a floppy disk Or is the question what is the oldest file that can be restored? Where restored means the file was somehow processed to a different format and/or media. ex. Using the DOS backup and restore commands.
Its a reasonable question becuase I have files that can be direct copied from removable media as far back and 1979. But it its pain in the neck to get old programs to unlock the compressed/encrypted data files and get them back to their original state.