Just so you know many pop-under script works fine with Firefox and Chrome but with IE it tends to open the pop-under on top of the IE browser. I don't know about this code above, if not great, if so know that you can use these brackets:
<![if !IE]>
<script src="path to your pop-under JS code" type="text/javascript"></script>
<![endif]>
Just add it at the bottom of the page before the </body> tag and put the path to your pop-under JS code inside of it. It will not process you pop-under JS code in any IE browsers. You will loose some traffic, not even 20% I think but you wont piss away your users.
