I've come across an issue where some contrib modules are not updated to work with PHP 5.3. The recommended solution is to downgrade to PHP 5.2.x.
I just started using Quickstart, Ubuntu, VirtualBox. (I know... a lot to learn.)
Anyway, I was curious if it is possible to either downgrade PHP to 5.2.x or install PHP 5.2.x alongside 5.3.x and switch between the two?