$agent = $_SERVER["HTTP_USER_AGENT"];
if(strpos($agent,"MSIE 8.0")||strpos($agent,"MSIE 7.0")||strpos($agent,"MSIE 6.0")){
header("location:a.php");
}else{
header("location:b.php");
}
if(preg_match('/MSIE\s+6/',$_SERVER['HTTP_USER_AGENT'])){
header("Location: a.php");
}else{
header("Location: b.php");
}
?>