var mymessage = "© 2004-2008 BROQUETAS, S.L.\n Todos los derechos reservados";
function rtclickcheck(keyp){
  if (navigator.appName == "Netscape" && keyp.which == 3) {
	alert(mymessage);
	return false;
  }
  if (navigator.appVersion.indexOf("MSIE") != -1 && event.button == 2) {
	alert(mymessage);
    return false;
  }
}
document.onmousedown = rtclickcheck