Ok, jeg fandt selv svaret ved at lede lidt rundt på nettet.
Til andre med samme problem er løsningen her:
SYMPTOMS:
Under IIS6.0 (.NET Server Family) the default installer of PHP will not
automatically configure the php executable to run and you will therefore run
into problems. Normally, just going in and setting it up as an ISAPI
extension would fix the problem, but with .NET Server Family, this is not
the case. There are some additional steps that you must take to ensure that
PHP will function properly under IIS6. These steps are listed below:
1. Download the latest PHP Windows Binaries from
http://www.php.net2. Run the installer and select the option to manually configure your
server. Select the installation path of your choice (default: c:\php\)
3. Once the setup is done, go into your IIS Server Manager and drop down to
the website that you wish to install PHP for. Set it up as you would under
a IIS5 server (Application Configuration, ISAPI Mappings) and setup the
php.exe to run the .php files. (You can do the same for .phps if you wish.)
4. The next step in getting this to work would to go the "Web Service
Extensions" under the IIS Services Manager. Once you have this open, select
"Add a new Web Service extension..." and set the extension name to ".php".
Select the "Add" button and navigate to the spot that you installed PHP.
Select the php.exe and hit "Ok". Select the checkbox at the bottom that
says "Set extension status to Allowed" and hit Ok.
