Shuffle array and spit out X number
/* set vars */
$numbers = range(1, 9);
shuffle($numbers);
$imgString = "/img/header-side-default";
/* loop */
foreach($numbers as $arr) {
$i++;
echo '<img src="'.$imgString.$arr.'.jpg" width="715" height="320" />';
if ($i == 3) break; /* change 3 to how many you want! */
}