Stoerelsen paa en div i javascript [IE Only]

<div id='mydiv'>
Hvor hoej er den her crap div??<br><br><br>Saa hoej?
</div>
<script>
height=document.all["mydiv"].clientHeight || document.getElementById("mydiv").offsetHeight
width=document.all["mydiv"].clientWidth || document.getElementById("mydiv").offsetWidth
alert(height+' '+width)
document.write(document.mytab.style.offsetHeight);
</script>