IIS not serving index.php as default page

Create a web.config file in your application directory

Paste this in the web.config, reset IIS and it works

configuration
system.webServer
defaultDocument
files
add value="index.php" /
/files
/defaultDocument
/system.webServer
/configuration

http://www.ozzu.com/programming-forum/tutorial-how-install-php-and-mysql-iis-t56303.html