//you have to pass to PopUp, the URL you want, then 'yes' or 'no' if you want the toolbar, "yes" or
//"no" if you want the menubar, and then the width and height in pixels. 
function PopUp(url,toolbar,menubar,w,h)
{ var windowProps = "status=yes,toolbar=" + toolbar + ",menubar=" + toolbar + ",location=no,scrollbars=yes,resizable,width=" + w + ",height=" + h;
  NewWin = window.open(url,"pop_up",windowProps)
  NewWin.focus();
}