To Remove index.php from ExpressionEngine URLs when using IIS7 do the following:
1. If one isn't there already, create a web.config file in the website's root directory.
2. If you are creating a new web.config file then the following code should work:
If there is already a web.config file in the root directory then you only need to add the rewrite rule section.
3. In ExpressionEngine go to Admin -> General Configuration and delete the name of your site's index page
(usually "index.php") in the "Name of your site's index page" field and select submit.
That's it - URL rewriting should be working in the same way as using .htaccess on Apache.