I guess I would have to ask you what you are specifically creating that you want to build outside Moodle (i.e. without using the built-in html editor.)
If you are building materials that are intended to be independent of the Moodle then the first question might be a political one, "Why would you use Word?"
Once past such matters the next question might be what your target format might be. Do you want your documents to be viewed as pdf, odt, xhtml
, or even flash, S5?
Another consideration might be how you expect the viewer to view the materials. Are there platform or other issues that limit what clients your viewers can employ to view the resources. Will you have to convert your materials to other formats to accommodate your viewers, etc.
You may find that building on google docs, publishing and then embedding is the way to go. I have demonstrated creating a google docs presentation and embedding in moodle to teachers to quite a few oohs and ahs (though frankly I think the audience would have been easily impressed with much less ;=} )
Converting Word to html can result in more complexity than you want in your life, so if your target is a web doc you might want to look at composing in amaya or nvu. OpenOffice does a nice job (and with appropriate macros allows me to create an xhtml doc withg working MathML)
If you are a Mac or have a pdf converter installed and plan to offer docs as pdf I would have to argue simplest is best, though Google Docs is still tough to beat as far as collaboration, on-line accessibility
and ease of import/export.
But to come full circle, the question I have is still, "Why not use Moodle's built in html text editors?"