Export Vista Mail messages back to Outlook Express

I had no trouble moving Outlook Express messages from one of my XP machines to my new Vista Business laptop. Now, however, I'd like to go in the other direction. I tried using the Export feature in Vista, but when I point Outlook Express to the folder containing the exported files, it reports, "no files found." I've already tried changing the attributes of both the folder and the exported files so that they were not readonly (that was the key to importing messages into Vista Mail).Any ideas?