Free extensions for Joomla!

Hi,

I have a timeout date for all products on my site which is 150 days. When they timeout they no longer appear on the site, but are still published in case I want to reuse them.

Could you tell me how to put this piece of code into the extension file to stop the sitemap from displaying timed-out products:

$database->setQuery ("SELECT * FROM jos_vm_product WHERE product_id = " . $db_browse->f("product_id") . " AND DATEDIFF(now(),`cdate`) > 150");

Thanks

Helen