Go to the IIS manager, and check out the setting for PHP files. Then, simply copy those setting into the HTML setting set, making any changes necessary. It's been a while since I worked in IIS, but I know that it's possible to do it this way.
Another way would be to find the registry entries for the PHP and HTML pages, and copy the PHP stuff into the HTML fields.
Hope this helps...
(And BTW, if you're running any kind of production server, Apache/Linux really is a better way to go...)