if (document.images) {	

   	sub_performance1_on = new Image();				sub_performance1_on.src="images/navigation/sub_performance1b.gif";  
	sub_performance1_off = new Image(); 			sub_performance1_off.src="images/navigation/sub_performance1a.gif";  
	
   	sub_performance2_on = new Image();				sub_performance2_on.src="images/navigation/sub_performance2b.gif";  
	sub_performance2_off = new Image(); 			sub_performance2_off.src="images/navigation/sub_performance2a.gif";  
	
   	sub_performance3_on = new Image();				sub_performance3_on.src="images/navigation/sub_performance3b.gif";  
	sub_performance3_off = new Image(); 			sub_performance3_off.src="images/navigation/sub_performance3a.gif";  

}