$(function() {
  $("a#whatisthis").mouseover(function(e) {
    var height = $('#whatisthis_div').height();
    var width = $('#whatisthis_div').width();
    var leftVal=e.pageX-(width/2)+"px";
    var topVal=e.pageY-height-20+"px"; 
    $('#whatisthis_div').css({left:leftVal,top:topVal}).show();
  });  
  $("a#whatisthis").mouseout(function(e) {
  	var non = "none";
    $('#whatisthis_div').css({display:non});
  });    
});