Hey guys, I'm a JS n00b but I'm looking to create a simple edit to this script. I'm using this JS to show/hide a section of my website. I want an image to change when the image is toggled.

Code JavaScript:
<script type="text/javascript">

Code HTML4Strict:
<a href="#" class="show_hide"><img src="http://www.sitepoint.com/forums/images/newsletterOpen.gif" alt="Newsletter Sign Up" /></a>