Center Popup Windows

<SCRIPT>
function getbrowserwidth()
{
	if (navigator.userAgent.indexOf("MSIE") > 0)
	{
		return(document.body.clientWidth);
	}
  else
  {
		return window.outerWidth;
	}
}
function getbrowserheight()
{
	if (navigator.userAgent.indexOf("MSIE") > 0)
	{
		return(document.body.clientHeight);
	} 
  else
  {
		return(window.outerHeight);
	}
}
var popup = new Object()
function CenterPopup(URL, width, height)
{
	// get center of browser window
	var X = getbrowserwidth() / 2
	var Y = getbrowserheight() / 2
	
	popup = window.open(URL, 'PopUp', 
		'scrollbars=yes ' +
		'width=' + width + ' ' +
		'height=' + height + ' ' +
		'top=' + (window.screenTop + (Y - (height/2))) + ' ' +
		'left=' + (window.screenLeft + (X - (width/2))) 
		)
	
	popup.focus()
}
</SCRIPT>
<A href="" onclick="CenterPopup('http://www.lewismoten.com/', 640, 480);return(false);">PopUp</A>