@Ajax.ActionLink giving you a brand new page? Wiping away your existing page, when all you wanted to do was update a div?
You probably just forgot javascript, or you have them included in the wrong order.
Try this in your script definition:
<script src="@Url.Content("~/Scripts/jquery-1.4.4.min.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/MicrosoftAjax.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/MicrosoftMvcAjax.js")" type="text/javascript"></script>
