According to the MediaWiki website, MediaWiki requires either PHP 5.3.0 or 5.3.2 because of a bug introduced in PHP 5.3.1, distributed in the latest version of XAMPP.
I downloaded the PHP 5.3.2RC2 VC6 Threadsafe version and tried installing it over the current PHP installation, then tried just replacing just the PHP from a .zip download. Neither of these attempts has the entry points Apache needs to use PHP.
Am I downloading the proper version of PHP to upgrade XAMPP? If not, do I use a different download? How do I upgrade?