Need to Downgrade php to 2.9.x in XAMPP or some other way???

[Inprogress]

Hello there all.

I have a slight problem at the moment. I need to develope a website offline (cheaper and quicker) but the extension that I will use does not work with PHP 3.X. How do I do this? I downloaded the tar.gz file from myPHP version 2.9.13. The extension that I will be using (oh, this is now refering to Joomla 1.5.15) is one from MightyExtensions.com.

I am a noob (and a boob) when it comes to the complexities of Linux and how to use the command line etc. So if I need to do this via the command line, please post the lines or point me to a website that explains is in detail as to how to do it. I've been using linux for about (Ubuntu 9.04) 6 months now.

Thanks for any help.

Happy trails