Cannot get PHP 4 install to oerate

I am running Windows XP, IIS, and INTERNET Explorer. I have installed PHP 4.3.10.10. I am tying to get the simple "Hello World" test php file to run. I have placed the test file in the default localhost web directory. I have verified it is in the correct directory by placing a small test html file there, and then executing that file from an http://localhost/myfile.htm from the IE address bar. It works fine. But executing http://localhost/hello,php gives the following error. Please help. How do I fix this problem. HTTP 403.1 Forbidden: Execute Access Forbidden Internet Information Services Thanks, Dave F.