<style type="text/css">

    #left {width:200px; min-height:500px;border:1px solid #ccc;float:left;}

    #right { width:740px;min-height:500px;border:1px solid #ccc;float:left;margin-left:10px;}

</style>

<div id="left">

    <ul>

        <li>@Ajax.ActionLink("news title a", "Contents",new{id=1}, new AjaxOptions {HttpMethod="Post",InsertionMode= InsertionMode.Replace, UpdateTargetId="news_content" })</li>

        <li>@Ajax.ActionLink("news title b", "Contents",new{id=2}, new AjaxOptions {HttpMethod="Post",InsertionMode= InsertionMode.Replace, UpdateTargetId="news_content" })</li>

    </ul>

</div>

<div id="right">

    <div id="news_content"></div>

</div>

        [HttpPost]

        public ActionResult Contents(int? id)

        {

            IList<string> list1 = new List<string>

            {

                "a news 1 title",

                "a news 2 title",

                "a news 3 title",

                "a news 4 title",

                "a news 5 title"

            };

            IList<string> list2 = new List<string>

            {

                "b news 1 title",

                "b news 2 title",

                "b news 3 title",

                "b news 4 title",

                "b news 5 title",

                "b news 6 title",

                "b news 7 title"

            };

            var model = list1;

            if (id != )

            {

                model = list2;

            }

            return PartialView(model);

        }