image = new Array(1); 
link = new Array(2);
image[0] = 'mainimg/topad_ibm.gif'//不同的图片
image[1] = 'mainimg/topad_ibm.gif'
image[2] = 'mainimg/topad_ibm.gif'
image[3] = 'mainimg/topad_ibm.gif'
image[4] = 'mainimg/topad_ibm.gif'
image[5] = 'mainimg/topad_ibm.gif'
image[6] = 'mainimg/topad_ibm.gif'
image[7] = 'mainimg/topad_ibm.gif'
image[8] = 'mainimg/topad_ibm.gif'
image[9] = 'mainimg/topad_ibm.gif'
image[10] = 'mainimg/topad_ibm.gif'
image[11] = 'mainimg/topad_ibm.gif'

link[0] = 'buy_product.php?pid=19' //不同的链接
link[1] = 'buy_product.php?pid=19'
link[2] = 'buy_product.php?pid=19'  
link[3] = 'buy_product.php?pid=19'
link[4] = 'buy_product.php?pid=19'  
link[5] = 'buy_product.php?pid=19'
link[6] = 'buy_product.php?pid=19'  
link[7] = 'buy_product.php?pid=19'
link[8] = 'buy_product.php?pid=19'  
link[9] = 'buy_product.php?pid=19'
link[10] = 'buy_product.php?pid=19'  
link[11] = 'buy_product.php?pid=19'





index = Math.floor(Math.random() * image.length);
document.write("<A HREF="+link[index]+">");
document.write('<IMG SRC="'+image[index]+'" height=70 width=570 border=0></A>');