I'm currently using Wordpress. My website is at www.payitforwardfriends.com.
For any post, where users can enter a comment, at the bottom there is a link that they can click to subscribe to future posts. I would like to make it so that instead of the link, there is a checkbox next to that sentence. When users click submit comment, IF the checkbox is checked, I want them to be directed to http://feedburner.google.com/fb/a/ma...?uri=IronWhisk and for their email from the comment form to be typed in. The code for getting the email from the form to google would be similar to...

<form style="padding:0px;text-align:left;" action="http://feedburner.google.com/fb/a/mailverify" method="post" target="popupwindow" onsubmit="window.open('http://feedburner.google.com/fb/a/mailverify?uri=IronWhisk', 'popupwindow', 'scrollbars=yes,width=550,height=520');return true">
<p><input type="text" style="width:126px; height:22px" name="email"/><input type="hidden" name="loc" value="en_US"/><input type="hidden" value="IronWhisk" name="uri"/>
<input type="submit" value="Sign Up" element id="searchsubmit"/></p></form>
This gets the email they typed in and puts it into google.

How do I do this?