if you are running Apache Server, you need to tell the server PHP exist.
Add the following to the top of your httpd.config file of your Apache Server:
ScriptAlias /php4/ "d:/PHP/"
AddType application/x-httpd-php4 .php
AddType application/x-httpd-php4 .php3
Action application/x-httpd-php4 "/php4/php.exe"
Path to your php on your drive
"d:/PHP/"
ScriptAlias /php4/ "d:/PHP/"