Here is the script i used and it works like a charm. I used the boolean method Ender suggested as the other ones using only the IE specific script adds something to IE but doesn´t take the original code out.
<script>runFancy = true;</script>
<!--[if IE]>
<script type="text/javascript">
runFancy = false;
</script> // <div>The HTML version for IE went here</div>
<![endif]-->
// Below is the script used for all other browsers:
<script src="accmenu/acac1.js" charset="utf-8" type="text/javascript"></script><script>ac1init_doc('',0)</script>