Here's my problem, I recently had to use IIS7 for one of my clients but he also wants PHP which is currently installed for my Apache setup on there. I can't find any ISAPI files in there, so I don't know what to do here...
For all your IIS7 + PHP needs start here:
The simplest way to install PHP on IIS7 is just to browse to that site on your server and click the big blue "Install PHP" button. This will launch the Web Platform Installer which will guide your through the install process.
To do this manually see this article:
There's also an alternative article on IIS.NET:
You will want one of the following binary packages for the "Install and Configure PHP" step: