You can also use OnComplete in Uploadify
Ref:
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <link rel="Stylesheet" type="text/css" href="CSS/uploadify.css" />
    <script type="text/javascript" src="scripts/jquery-1.3.2.min.js"></script>
    <script type="text/javascript" src="scripts/jquery.uploadify.js"></script>
</head>
<body>
    <form id="form1" runat="server">
    <div style="padding: 40px">
        <asp:FileUpload ID="FileUpload1" runat="server" />
        <table class="rounded_corners" id="attachedfiles">
        </table>
    </div>
    </form>
</body>
</html>
<script type="text/javascript">
    $(window).load(
    function () {
        $("#<%=FileUpload1.ClientID %>").fileUpload({
            'uploader': 'scripts/uploader.swf',
            'cancelImg': 'images/cancel.png',
            'buttonText': 'Browse Files',
            'script': 'Upload.ashx',
            'folder': 'uploads',
            'fileDesc': 'Image Files',
            'fileExt': '*.jpg;*.jpeg;*.gif;*.png',
            'multi': true,
            'auto': true,
            'onComplete': function (event, ID, file, response, data) {
                $("#attachedfiles").append("<tr><td>" + file.name + "</td><td><img src=" + file.filePath + " height='100' width='100' /></td><td><a href = 'javascript:;'>[x]</a></td></tr>");
                //alert("Uploaded");
                // Call Ajax Web method
            }
        });
    }
);
</script>
Thank You.