function centerPop(theURL,theName,width,height) {

	x = (window.screen) ? (window.screen.availWidth - width)/2 : (640 - width)/2 ;
	y = (window.screen) ? (window.screen.availHeight - height)/2 : (480 - height)/2 ;

	popupWin = window.open(theURL,theName,'toolbar=no,location=no,status=no,menubar=no,scrollbars=no,resizable=no,width='+width+',height='+height+',screenX='+x+',screenY='+y+',top='+y+',left='+x);
	popupWin.focus();
}
// FUNCTION CALL: onClick="centerPop('popup.html','win','200','200')"