If you're like most, you don't install the Office client on your servers. In order for the Index server to have the Office 2007 IFilters, you'll need to download this filter pack and install it on your Index server.
http://www.microsoft.com/downloads/details.aspx?FamilyId=60C92A37-719C-4077-B5C6-CAC34F4227CC&displaylang=en
Bill English
Mindsharp