Use jQuery from CDN, because it is usually cached. Always use fallback (Sometimes Google fails).

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js"></script>

<script type="text/javascript">

if (typeof jQuery == 'undefined')

{

document.write(unescape("%3Cscript src='/path/to/your/jquery' type='text/javascript'%3E%3C/script%3E"));

}

</script>