How can I have the server parse html files as if they were php?

This only applies to linux hosting accounts:

Inside the directory with the html files, create a .htaccess file and inside, place the following -

AddHandler application/x-httpd-php5 .html

For windows hosting accounts:

Inside your web.config file, placed the following between the <handlers> tags:

<add name="html via php cgi" path="*.html" verb="*" modules="FastCgiModule" scriptProcessor="C:\Php5\php-cgi.exe" resourceType="Unspecified" />