Here's how I do it.
.htaccess file
Code:
RewriteEngine On
RewriteRule ^(.*)\.htm$ $1.php [L]
Example: http://www.coastalmobile.com/mobile-...iners-cove.htm
That page has an .htm extention - however those properties on the page are dynamically generated.
This way you can have the page appear as if it's an .html page to the search engines. Just as long as you have an apache webserver this will work perfectly and the searchengines, and users will never need to know that it's actually a php file. One of the big advantages I find with a php site is the ability to easily do includes (there are ways without php ) - but anyways - It's always nice to have PHP.