DaveR,
There is another solution, if you are like me and just like using the .html extension..
If you have .htaccess file use available to you then you can add this to the beginning of the file and upload it, then your server will parse htm html and php files for php code.
AddType application/x-httpd-php .html .php .htm
AuthUserFile /dev/null
AuthGroupFile /dev/null
Quite honestly the second and third lines, I'm not sure if they are necessary, but I've always included them, just in case... I'm sure someone here that knows alot more then I can tell you for sure.
If using .html as an extension is not an issue with you then you may not want to use this method, because I assume there is some sort of performance hit on your server based on parsing all html docs for php code, but I've never noticed a difference.
showman