This is how I autoload all the classes in my controllers folder,
# auto load controller classes
function __autoload($class_name)
{
__autoload() function should not be use because it is not encourged. Use spl_autoload(), spl_autoload_register() instead. __autoload() just can load one class but spl_autoload() can get more than 1 classes. And one thing more, in future __autoload() may deprecated. More stuff can be find on http://www.php.net/manual/en/function.spl-autoload.php