function disableRightClick(e)
{
  var message = "Right click disabled";
  
  if(!document.rightClickDisabled) // initialize
  {
    if(document.layers) 
    {
      document.captureEvents(Event.MOUSEDOWN);
      document.onmousedown = disableRightClick;
    }
    else document.oncontextmenu = disableRightClick;
    return document.rightClickDisabled = true;
  }
  if(document.layers || (document.getElementById && !document.all))
  {
    if (e.which==2||e.which==3)
    {
      alert(message);
      return false;
    }
  }
  else
  {
    alert(message);
    return false;
  }
}
disableRightClick();


<!--

//Disable right mouse click Script
//By Maximus (maximus@nsimail.com) w/ mods by DynamicDrive
//For full source code, visit http://www.dynamicdrive.com

var message="Function Disabled!";

///////////////////////////////////
function clickIE4(){
if (event.button==2){
alert(message);
return false;
}
}

function clickNS4(e){
if (document.layers||document.getElementById&&!document.all){
if (e.which==2||e.which==3){
alert(message);
return false;
}
}
}

if (document.layers){
document.captureEvents(Event.MOUSEDOWN);
document.onmousedown=clickNS4;
}
else if (document.all&&!document.getElementById){
document.onmousedown=clickIE4;
}

document.oncontextmenu=new Function("alert(message);return false")