function popupwin(filename, windowname, width, height)
{
var left = (screen.width - 700)/2;
left = left<0?0:left;
var top  = (screen.height - 500)/2;
top = top<0?0:top;
newWindow = window.open(filename,windowname
,"location=0,scrollbars=1,menubar=0,toolbar=0,status=0,resizable=0,directories=0,left="+left+",top="+top+",width="+width+",height="+height);
newWindow.moveTo(left,top);
}