If you have a file called index.html and you want to show it in index.php, I think your index.php file can just look like this:
PHP Code:
<?php
readfile("/path/to/index.html");
?>
(I haven't tried that, but I think it would work.)
As I said before, I've never done what you want to do, but I did google it and found this -
http://php.about.com/od/advancedphp/p/html_php.htm According to that, the line to add to your .htaccess file is:
Code:
AddType application/x-httpd-php .html
If that doesn't work, then are you sure your .htaccess file is working? Your host could have the server set up to not allow .htaccess files (they may have AllowOverride set to None instead of All).