Versuchen Sie Folgendes:
$('input[name=system]').click(function(){
var ids = [];
$('input[name=system]:checked').each(function() {
ids.push($(this).attr('id'));
});
ids = ids.join(",");
$.get("review.php", {param: ids},
function(data) {
$("div#update").html(data);
}
);
});
Und in Ihrem PHP:
if (isset($_GET['param'])) {
$param = "('" . str_replace(",", "','", $_GET['param']) . "')";
}
$qry = mysql_query("SELECT * FROM reviews WHERE os IN $param") or die(mysql_error());