Windows – Upgrade PHP 5.1.x to 5.3.x with XAMPP for Windows

Using Windows XP SP3. I installed the xampp to d:\xampp.
I started it and everything worked fine (at least the indications were good).
I want to use MediaWiki and it says that it can't work with PHP5.1 which is the version installed by XAMPP.

I followed the instructions I found in this thread, but now the Apache service does not start.
The control panel for XAMPP says that the Apache service started though it does not show an indication of running.

I am not familiar with the XAMPP at all. I don't know where to look for the error.

Question: How do I upgrade to PHP 5.3

I Must have gone blind or something…
Reinstalling XAMPP revealed that the version of the PHP is 5.3.1 as suggested by itadok's answer

My mistake was that I checked the phpmyadmin for the version and it stated server version and not PHP version.