Can’t help you with XAMPP, sorry. I have never used it. I know it is pre-configured to contain Apache as the Webserver and mySql as the DB, along with PHP and phpMyAdmin (web-based management of mySql). The only part of XAMPP that you really need is the PHP installation. The rest is “overkill” and for the most part, unused.
Here is a Tutorial on setting up a basic PHP installation with IIS. It isn’t that difficult once you have done it a couple times, and learned the requirements, some of which are a bit cryptic to troubleshoot at first…