var rightClick = {
disableIE: function(){
    if(document.all){return false;}
},

disableNS: function(e){
    if(document.layers || (document.getElementById && !document.all)){
      if(e.which == 2 || e.which == 3){return false;}
    }
},

disable: function(){
    if(document.layers){
      document.captureEvents(Event.MOUSEDOWN);
      document.onmousedown = this.disable;
    }
    else{
      document.onmouseup = this.disableNS;
      document.oncontextmenu = this.disableIE;
    }
    document.oncontextmenu = new Function("return false");
}
}

rightClick.disable();