When you try to install magento 1.3.x on Blacknight Unix hosting you may (immediatly) get the following error:

'Whoops, it looks like you have an invalid PHP version.'

Well, don't panic, this is a very similar situation to the one outlined in this earlier drupal post. Your hosting does have the correct version of PHP installed (5.2.x) it's just that the default version is an older one. You just need to disable the older PHP version, wait a few minutes and things should be ok then.

When you try to install new modules onto a Drupal setup hosted on a Blacknight.ie Unix hosting plan do you get errors like the following about the installed PHP version?

"This module requires PHP version 5.2.* and is incompatible with PHP version 4.4.7."

If so don't panic, your hosting paln will almost certainly have PHP 5.2 installed and configured, all you have to do is to go to the control panel and disable PHP 4.x support, this will then allow PHP 5.2.x to shine through and should keep your modules from complaining!