if(document.images)
    {
     imagemap_default = new Image();
     imagemap_default.src = 'images/buttons/imagemap.gif';
     
	 imagemap_mission = new Image();
     imagemap_mission.src = 'images/buttons/mission.gif';
     
	 imagemap_history = new Image();
     imagemap_history.src = 'images/buttons/history.gif';
     
	 imagemap_contact = new Image();
     imagemap_contact.src = 'images/buttons/contact.gif';
   
    }



    function rollOver(iName,iState)
    {
      if(document.images)
      {
        document.images[iName].src = eval(iName + '_' + iState + '.src');
      }
    }