[jQuery] Trying to copy img src attr to another img

[drm]

See http://dev.slyd.us/drupal/foundation/node/59

I want to have a mouseover of one of the small images make it replace
the larger one. This is what I'm trying:

'$(document).ready(function() {
      var source2 = $("div.listingimagetwo img").attr("src");
      var source1 = $("div.listingimageone img").attr("src");

      $(".listingimagetwo").hover(
            function () {
                $("div.listingimage img").attr("src", source2);
            },
            function(){
                $("div.listingimage img").attr("src", source1);
                );
            }
      });

I also tried using div.listingimagetwo[img] instead of
div.listingimagetwo img

Is there a plugin that you do this?

The site also uses thickbox to display these images. Does that
conflict? I was brought on to add this function, so I can't change the
html structure, though I could ask the client if need be.

Thanks for any pointers.