In the example:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/odc_vsto2005_ta
/html/OfficeVSTOBenefitsRegistration.asp
is shown how to get the document to the client using the browser. I've tried
this myself and is does work.

But... Be aware of the section:
------------------
Opening Word in a New Window
Typically, when Internet Explorer downloads a Word document, it attempts to
host Word inside of the Internet Explorer window and merge the menu and tool
bars. Microsoft Windows allows you to change this behavior so that the
document opens in a new Word window. However, if you have changed the
default setting of the Browse in same window command for Word documents, a
known issue with Word 2003 prevents the customization assembly from loading.
You do not receive any errors, but when the benefits registration form
downloads, no code executes.
---------------

If this is configured wrong the document IS loaded, but the assembly refuses
to work without any notice or clue why not!

Hope it helps,

-= Maarten=-
MVP - Visual Developer - VSTO
http://blogs.officezealot.com/maarten