The "save as web page" option in MS Word creates a single long HTML document. There are several 3rd party tools that let you create a set of linked documents instead. Whenever a "header" appears in the document a new linked page is generated.
A cheap and flexible tool for doing this is logictran. For an example of its output, see the Girl Scout Manual at the Troop 680 website.
I did discover one tricky bug in the program: the little "gif" images used for navigation arrows are not properly linked into the output. To solve this, manually copy the "images" directory from Program Files\Logictran\doc\images into your destination directory. Then, in the program r2net in the option for files set the location of the images directory to "." (a period).