Web Platform Installer is a tool, which contains many libraries, components and ready to use solutions. This tool very useful, because allow to save many time. Also, it is free tool and you can download it and install on your machine.
However, speech now not about it. Recently there was updating WPI in which there was a driver for support SQL Server in PHP. It is easy to be convinced of it if to start an installing package.
Thus, developing on PHP you can use all benefits of usage of SQL Server. I will remind, that support PHP in IIS7 exists already for a long time and works not worse, than on *nix.