jquery code for drupal 6
if you don't want to upgrade the jQuery version. Please try this.

http://jsfiddle.net/ravindrasingh22/3HVpW/

$(document).ready(function() {

    var changeTooltipPosition = function(event) {
      var tooltipX = event.pageX - 8;
      var tooltipY = event.pageY + 8;
      $('div.tooltip').css({top: tooltipY, left: tooltipX});
    };

    var showTooltip = function(event) {
      $('div.tooltip').remove();
      $('&lt;div class="tooltip"&gt;I\' am tooltips! tooltips! tooltips! :)&lt;/div&gt;')
            .appendTo('body');
      changeTooltipPosition(event);
    };

    var hideTooltip = function() {
       $('div.tooltip').remove();
    };

    $("label#tooltip2'").bind({
       mousemove : changeTooltipPosition,
       mouseenter : showTooltip,
       mouseleave: hideTooltip
    });
});


HTML Code

&lt;label id="tooltip2"&gt;Mouse Hover here&lt;/label&gt; 


CSS Code

#hint{
     cursor:pointer;
    }
    .tooltip{
        margin:8px;
        padding:8px;
        border:1px solid blue;
        background-color:yellow;
        position: absolute;
        z-index: 2;
    }