Posicionar div nas coordenadas do mouse

JavaScript

function showdiv(event){
//La variable IE determina si estamos utilizando IE
var IE = document.all?true:false;

var tempX = 0;
var tempY = 0;

if(IE) { //para IE
tempX = event.x
tempY = event.y
if(window.pageYOffset){
tempY=(tempY+window.pageYOffset);
tempX=(tempX+window.pageXOffset);
}else{
tempY=(tempY+Math.max(document.body.scrollTop,document.documentElement.scrollTop));
tempX=(tempX+Math.max(document.body.scrollLeft,document.documentElement.scrollLeft));
}
}else{ //para netscape
document.captureEvents(Event.MOUSEMOVE);
tempX = event.pageX;
tempY = event.pageY;
}

if (tempX < 0){tempX = 0;}
if (tempY < 0){tempY = 0;}

document.getElementById('divName').style.display='block';
document.getElementById('divName').style.top = (tempY-100)+"px";
document.getElementById('divName').style.left = (tempX+15)+"px";
return;
}

<p onclick="showdiv(event);">Link</p>
<div id="divName">Conteúdo</div>