<?php 
$banners[0]['img']="images/banner1.jpg"; 
$banners[0]['alt']="Banner 1"; 
$banners[0]['url']="http://www.sitem.com"; 
$banners[1]['img']="images/banner2.jpg"; 
$banners[1]['alt']="Banner 2"; 
$banners[1]['url']="http://www.sitem.com"; 
$banners[2]['img']="images/banner3.jpg"; 
$banners[2]['alt']="Banner 3"; 
$banners[2]['url']="http://www.sitem.com"; 
$banners[3]['img']="images/banner4.jpg"; 
$banners[3]['alt']="Banner 4"; 
$banners[3]['url']="http://www.sitem.com"; 
$banners[4]['img']="images/banner5.jpg"; 
$banners[4]['alt']="Banner 5"; 
$banners[4]['url']="http://www.sitem.com"; 
$banners[5]['img']="images/banner6.jpg"; 
$banners[5]['alt']="Banner 6"; 
$banners[5]['url']="http://www.sitem.com"; 
$id_banner = array_rand($banners); 
?> 
<a href="<?php echo $banners[$id_banner]['url']; ?>"><img src="<?php echo $banners[$id_banner]['img']; ?>" alt="<?php echo $banners[$id_banner]['alt']; ?>" border="0"/></a>

<a href="<?php echo $banners[$id_banner]['url']; ?>" target="_blank"><img src="<?php echo $banners[$id_banner]['img']; ?>" alt="<?php echo $banners[$id_banner]['alt']; ?>" border="0"/></a>