Jason recently commented on the OpenOffice.org Docs In Fx Part 2 entry:

Thanks for the great article! Very useful.I wonder if it is possible to open a word .doc within Firefox using OpenOffice and this method?

Excellent question! Never really thought about it but figured it should work if I could get Firefox to associate Word Documents with OpenOffice. As it turns out yes you can. Further, you don’t need to do anything else other than to activate the Mozilla Plug-in from within OpenOffice.org via the Tools Menu, Options…, Internet and then under Mozilla Plug-in check the enabled box. It will work if you have already associated Microsoft Office documents with OpenOffice. This is done when you installed OpenOffice (see below).