PHP Help & php.ini & 404 errors

Yes, I am a newbie on php but would really appreciate any help with my setup and config of php on Win 2003 server. I have recently installed php to run on my web server but have been unsucessful in making the program open a simple app. ie get a page not found 404 error… I have installed previous comilation programs like Java and think I have set up the environmental variables, the server side extensions, and the confusing one the php.ini file which I am unsure which version and how it should reside. thanks in advance. DH