jquery non è il mio forte e il codice di sotto non so se vada

codice:
    <script type="text/javascript">
        // <![CDATA[
        $(document).ready(function ()
            {
                for (var i = 2; i <= 10; i++) $("#post" + i).hide();

                $("#posti").change(function ()
                {
                    for (var i = 2; i <= 10; i++) $("#post" + i).hide();
                    var j = $(this).val();
                    for (var k = 2; k <= j; k++) $("#post" + k).show();
                });

            }
        );

        // ]]>
    </script>
</head>
<body>
    <form id="form1" runat="server">
        <div class="row">
            <select name="posti" id="posti" size="10" multiple="True">
                <option name="01" value="1">01</option>
                <option name="02" value="2">02</option>
                <option name="03" value="3">03</option>
                <option name="04" value="4">04</option>
                <option name="05" value="5">05</option>
                <option name="06" value="6">06</option>
                <option name="07" value="7">07</option>
                <option name="08" value="8">08</option>
                <option name="09" value="9">09</option>
                <option name="10" value="10">10</option>
            </select>
        </div>
        <hr />
        <div>
            <div class="row" id="post2">prova2</div>
            <div class="row" id="post3">prova3</div>
            <div class="row" id="post4">prova4</div>
            <div class="row" id="post5">prova5</div>
            <div class="row" id="post6">prova6</div>
            <div class="row" id="post7">prova7</div>
            <div class="row" id="post8">prova8</div>
            <div class="row" id="post9">prova9</div>
            <div class="row" id="post10">prova10</div>

        </div>
    </form>
</body>
</html>