Can't get PHP to work properly...

I am trying to get PHP functional on windows XP using APACHE 2.x as the
server. I have read the installation text and tried to find the answer
on the Google "old posts". I believe I have updated the correct paths
in in "http.conf" and "php.ini" etc. But am stuck. When I run
"test.php" using the URL http://localhost/test.php in my browser, I
get notepad popping up with the "test.php" code being displayed. Does
anyone know what might be wrong?

Thanks,
RABMissouri