[Zope] Indexing msword docs in ZCatalog

Hi, I've got a ZCatalog that takes care of indexing all my pages so that I can use a search feature on my web page. The page also contains a DocumentLibrary so that an administrator can upload documents onto the page and then refresh the catalog. I'm managing to upload succesfully pdf, text and msword documents but am having a problem with the indexing of the msword docs.... as far as I know the DocumentFiles added to the DocumentLibrary supports full text searchability for msword docs. Am I missing something? do I need to convert the docs in any way before uploading for them to be catalogued succesfully? Cheers Ruth