Load jQuery 1.7.1 from the CDN. If it loads put it into noConflict mode. If it doesn't, load the local copy. Keep checking until the local copy loads and put that into noConflict mode.

jQuery testing and fallback

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min1.js"></script>
<script>
  var $$;

  // If 1.7.1 is loaded, put it into noConflict mode
  if(window.jQuery().jquery = '1.7.1') {
    $$ = $.noConflict(true);
  } else {
    // If it is not loaded, load the local version
    document.write("<script src='/js/jquery-1.7.1.js'>\x3C/script>");

    // Keep checking until it is loaded
    var intervalID = window.setInterval(function() {
      // If it is loaded, put it into noConflict mode and clear the interval
      if(window.jQuery().jquery == '1.7.1') {
        $$ = $.noConflict(true);
        window.clearInterval(intervalID);
      } else {
        // keep trying
      }
    }, 1000);
  }
</script>