Customer Support

If you want to let people download an OpenOffice document with an .odt
extension and are having a problem with binary data from the document
opening inside the browser, just add the following directive to  an
.htaccess file located above all the directories where you want it to
operate:

   AddType application/vnd.oasis.opendocument.text .odt

Doing that will change the behavior to make the user's browser prompt to
either open the document with OpenOffice (or some other application) or
"Save to Disk."

To prevent .docx documents from being displayed in browsers you can add
the following to a .htaccess which should force the browser to download
the file as opposed to display it:

 AddType 
application/vnd.openxmlformats-officedocument.wordprocessingml.document
.docx

More info:
http://technet.microsoft.com/en-us/library/cc179224.aspx