Решение:
<script type="text/javascript" src="https://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.min.js"></script> <script type="text/javascript"> if (typeof jQuery == 'undefined') { document.write(unescape("%3Cscript src='/js/jquery-1.6.1.min.js' type='text/javascript'%3E%3C/script%3E")); } </script>