Almost every popular PHP app that you may want to run on IIS7 requires MySQL. I just ran across a couple of really great articles which provide step by step instructions for how to get MySQL and PHPMyAdmin running.
First, learn how to get MySQL going on Windows 2008 by reading this tutorial: Install MySQL on IIS7 Server 2008
PHPMyAdmin, for those who haven’t used it before, is a handy PHP app that lets you do database administration via your Web browser. Handy for getting a database or user created, running ad hoc queries, and so forth. Learn how to install it by reading this tutorial: Install PHPMyAdmin on IIS7 and Server 2008
The TrainSignalTraining.com guys have a lot of really detailed, step-by-step tutorials on IIS7 for a variety of topics that are free and definitely work checking out.