jquery :contains and IE < 9

I'm using this script on my site and it is working fine in all browsers but it doesn't load the page in IE before 9. Do you know what could be the problem?

<script type="text/javascript">
jQuery.noConflict();
(function($) {

    $("div.boxPrdlistVet b:contains('Consulte-nos')").html("<b>ESGOTADO<br />Consulte-nos</b>");

})(jQuery)开发者_高级运维;
</script>

I can't add classes to the <b> elements. I'm using JQuery 1.6.3. I tried the IS statement but didn't work. I'm new with JQuery, probably I didn't try the right way...

If you want take a look on the wall site, here it is.