If you're not wedded to PWS, check out the free BadBlue server (http://badblue.com) which now supports PHP. It is tiny (the server itself is about 60K) and you can be up and running in (literally) 20 seconds.
Once you're running BadBlue and want to add PHP support, stop the server by pressing the stop button, and edit the "\program files\badblue\pe\ext.ini" file, adding the two lines:
[SERVICES]
extension1=php,c:\where-you-put-php\php.exe
Then press the start button. If you're just looking for a simple way to learn, develop or deploy PHP apps, this is worth checking out.