Someone

<?php
include('header.php');
include('sideleft.php');

    // NOTE: conditional includes always get parsed,
    //       even if the condition is not met!  make
    //       sure there are no unintended side effects

    switch ($_GET['act']) {
        case "1": include('files.php');
        break;
        case "2": include('request.php');
        break;
		case "3": include('contact.php');
		break;
		case "4": include('staff.php');
		break;
        default: include('main.php');
        break;
}
include('sideright.php');
include('footer.php');
?>