[php] Using XAMPP, how do I swap out PHP 5.3 for PHP 5.2?

I couldn't get this working. Started with PHP 5.3, then tried to switch to PHP 5.28 from xampp-win32-1.7.0.zip. Couldn't get it to work. Then, I got smart and figured out i was working with XAMPP and you can install it wherever you want, so I did a fresh install from scratch with xampp-win32-1.7.0.zip. The whole point of working with XAMPP is so you don't have to fuss with the sysadmin stuff. Using it in that context got me up and running in no time.