var nn4 = (document.layers) ? true:false;
var ie4 = (document.all) ? true:false; //ie 4+
var nn6 = (document.getElementById && !document.all) ? true:false; //nn6
function ehan( evnt )
{
  if( evnt.which == 3 )
  {
    return false;
  }
  return true;
}

if (nn4) 
{
	document.captureEvents( Event.MOUSEDOWN );
	document.onmousedown = ehan;
}