var mymessage = "(c) 1999,2000,2001,2002,2003, 2004 copyright www.ibizaholidays.com";

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