Open external site in a popup if no product description available

[mmphis]

Hello, maybe someone can help to do the next thing:

If product description is empty, than need to open a popup window with external site provided in product url. So if we are in browsepage and product has full description, than if we click on read more or product title we see flypage with all info, but if i leave product desciption empty - than after user clicks on read more or product title he see a popup window with external website and add to cart button at the top. After user clicks on add to cart popup window closes.

All information will be provided, such as price... need only a popup with add to cart button and content of external site.

Thanks

[mmphis]

Popup is working now, i added this code to product browsepage:

<script language="javascript" type="text/javascript">
<!--
var newwindow;
function poptastic(url)
{
   newwindow=window.open(url,'name','height=600,width=850,top=120,scrollbars=yes,');
   if (window.focus) {newwindow.focus()}
}

// -->
</script>

<a href="javascript:poptastic('<?php echo $product_url ?>');">Pop up</a>

Now popup show web site which i write in product url. How to put cart button, price and product name to my popup window? Thanx
-----------------
Also can't make it to work with lightbox. tried to use joomla lightbox with class="modal">, but lightbox can't show virtuemarts <?php echo $product_url ?>.

[mmphis]

now lightbox works. I used yootheme plugin. But how to put product name, price and add to cart to lightbox?