I am trying to do something like this on tpl_shopping_cart_default.php

Code:
if ( $cart_quantity == "1" ) {
	echo "Did you know a second box will ship for free!<br />";
}
?>
is that right? When there is only one item in shopping cart, I want to display the message above.

is the variable $cart_quantity right for the number of items in cart?

( My first attempt at php, be gentle )