FAQ: Is it possible to install your software on a Windows server?

Yes - if you can install Apache+MySQL+PHP on Windows and use it instead of the default IIS. We're not making any movement towards IIS compatibility.
The Apache web server is compatible with most OS's and we don't see any advantages to focusing on just IIS or any other platform-specific web server. There are some packages that already include Apache+MySQL+PHP and are very easy to install and administer - this one, for example: http://www.wampserver.com