http://learn.iis.net/page.aspx/557/tran ... webconfig/
Introduction
Many PHP applications are distributed with configuration files for the Apache Web server. These configuration files (usually called .htaccess files) contain a number of settings that can be used for integrating the application with the capabilities of the Web server.
IIS 7 uses a file called Web.config to hold settings for integration with applications. The Web.config file contains information that control module loading, security configuration, ...