var b1= new Array(4);
 var l1= new Array(4);


 b1[0] = 'montreal-service-com.jpg';  
 l1[0] = 'http://montreal-service.com';  

 b1[1] = 'www-buyhomebc-com2.jpg';  
 l1[1] = 'http://www.buyhomebc.com';  

 b1[2] = 'montreal-service-com.jpg';  
 l1[2] = 'http://montreal-service.com';  

 b1[3] = 'www-buyhomebc-com2.jpg';  
 l1[3] = 'http://www.buyhomebc.com';  

 var rand_no = Math.floor(4*Math.random());

 var str = '<div><a href="'+l1[rand_no]+'" target="_blank"><img width="160" height="80" src="http://biznes.ca/img/b/'+b1[rand_no]+'" border="0" alt="" /></a></div>';

 document.write(str);