Marble Host offers PHP4 and PHP5. This allows you to easily manage the way your PHP scripts are handled and run by the web server. You can setup PHP version in the
control panel. PHP5 is now officially supported on all servers.
There are several differences in the configuration and in the way certain functions and expressions are handled. PHP4 has a larger installed base at this point but since PHP is a server side script, it will hardly affect the end user. PHP5 is simply a newer release which offers its own improvements and add-ons. However, there might be some incompatibility issues when certain PHP scripts are run on both versions. You should use PHP5 only if it is required by the script author.
PHP 4 and PHP 5