<p>Are there any "all-in-one" installers for php + mysql on iis? Preferably with a gui configuration interface.</p>

I don't know of any all-in-one installers for both MySql and PHP, but PHP itself comes with an automated installer that will attach itself to IIS - but the preferred method is still manual (the automated procedure only uses CGI). There are plenty of how-to pages on the web that give you the step-by-step procedure required to get setup (and these differ based on your version of IIS) - I suggest you use one of those instead.
Some links to get you started:
PHP Documentation
Installing PHP 5 on IIS in 5 simple steps