APPLEDOGX I have had trouble that sometimes the .doc is not appended when exporting word documents. Make sure it appears in the file name for the Windows attachment in the email. Also, Windows users get odd characters appended to the .doc file extension, at least in Pages 08, if the file name contains international characters, such as accents, tildes, etc. I always take them out, then the Windows user usually can open the word document exported with no trouble. Hope this helps you a bit.
(Version 3.0.3)