I am working on testing some mortgage calculators done with php, the code is freeware which I have modified but is encoded with ionCude.

I want to downloan the ionCube loader onto XAMP but am unsure which version to download (or even if this is the correct way to do it!)

I have win xp with linux XAMP and there are tons of options

link for encoder site is http://www.ioncube.com/loaders.php

any help would be appreciated.

Choose the loaders for the operating system you're on and then follow the installation instructions linked to on that page.