if (document.images) {
 img1_on =new Image();
 img1_on.src ="images/btn1_on.jpg";
 img1_off=new Image();
 img1_off.src="images/btn1_off.jpg";


 img2_on =new Image();
 img2_on.src ="images/btn2_on.jpg"; 
 img2_off=new Image();
 img2_off.src="images/btn2_off.jpg"; 


 img3_on =new Image();
 img3_on.src ="images/btn3_on.jpg"; 
 img3_off=new Image();
 img3_off.src="images/btn3_off.jpg"; 


 img4_on =new Image();
 img4_on.src ="images/btn4_on.jpg"; 
 img4_off=new Image();
 img4_off.src="images/btn4_off.jpg"; 


 img5_on =new Image();
 img5_on.src ="images/btn5_on.jpg"; 
 img5_off=new Image();
 img5_off.src="images/btn5_off.jpg"; 


 img6_on =new Image();
 img6_on.src ="images/btn6_on.jpg"; 
 img6_off=new Image();
 img6_off.src="images/btn6_off.jpg"; 


 img7_on =new Image();
 img7_on.src ="images/btn7_on.jpg"; 
 img7_off=new Image();
 img7_off.src="images/btn7_off.jpg"; 

 img8_on =new Image();
 img8_on.src ="images/btn8_on.jpg"; 
 img8_off=new Image();
 img8_off.src="images/btn8_off.jpg"; 
}