Hi =?Utf-8?B?UmFtcw==?=,
Irrelevant. Word documents are not HTML.
Relevant. Not all web documents are HTML. ;-)
The browser and server need to work out between them what happens when the user
clicks on a link to, say, a PDF. Or a DOCX.
If the mime types are set incorrectly, the browser may try to open Office 2007
files as ZIP files rather than launching them in the correct Office app. More
on that here (from a PPT perspective, but change the app names and extensions
and the info should be good for Word too):
PowerPoint 2007 files don't download correctly from a Web Server, open as zip
files
http://www.pptfaq.com/FAQ00911.htm
There's a link to a list of suggested MIME types too.