Marketpress: If out of stock then...

Hey guys

I want to show a form on my Marketpress product page if a product is out of stock and hide it if the product is in stock.

Is there is a PHP statement that would allow me to use something like this (obviously just an example):

<?php if(stock_amount('0') )  { ?>
 <?php } else {?>
 <?php } ?>

Any help would be greatly appreciated