Problem installing in Win2003 Server SP1

I have been trying for several days to get PHP 4.x installed on my Win2003 SP1 server. I am doing the manual (isapi) install. I modified my php.ini file, I think correctly..... And added the extension into IIS6, pointing to the \php directory and the php4isapi.dll file. When I try to view a php file, even one that returns the basics showing if PHP is running or not, I get a 'page can't be found' Can anyone tell me what I might be doing wrong? Thanks, Steve