Magento - How to track conversions from Google Adwords

Include the code below in app/design/frontent/default/your_template/template/checkout/success.phtml

Below:

<?php echo $this->__('Your order # is: %s', $this->getViewOrderUrl(), $this->getOrderId()) ?>.<?php else :?>
<?php echo $this->__('Your order # is: %s', $this->getOrderId()) ?>.<?php endif;?>

<?php //-------------------------------------------
// START ADWORDS CONVERSION VALUE TRACKING CODE
//-------------------------------------------$order_details = Mage::getModel('sales/order')->loadByIncrementId(Mage::getSingleton('checkout/session')->getLastRealOrderId());$adwords_saleamt = $order_details->subtotal; ?>
<!-- Google Code for Purchase/Sale Conversion Page -->
<script language="JavaScript" type="text/javascript">
<!--
var google_conversion_id = XXXXXXXX---YOURIDHERE---XXXXXX;
var google_conversion_language = "en";
var google_conversion_format = "1";
var google_conversion_color = "ffffff";
var google_conversion_label = "purchase";
var google_conversion_value = "<?php echo $adwords_saleamt; ?>";//--></script><script language="JavaScript" src="http://www.googleadservices.com/pagead/conversion.js"></script><noscript>
<img height="1" width="1" border="0" src="http://www.googleadservices.com/pagead/conversion/XXXXXXXX---YOURIDHERE---XXXXXX/?label=purchase&amp;guid=ON&amp;script=0"/>
</noscript>
<?php//-------------------------------------------
// END ADWORDS CONVERSION VALUE TRACKING CODE
//-------------------------------------------?>

From http://www.magentocommerce.com/boards/viewthread/22973/P0/