ASP.NET MVC 2: How to master common update/create scenarios with popups using jQuery

Question

I have an Index page. In the contentwrap div the overlay is rendered and popuped by jQuery. The gridcontainer shall be updated via ajax.

    <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
        <h2>
            List of Employees</h2>
        <br />
        <div id="gridcontainer">
            <% Html.RenderPartial("Grid", Model); %>
        </div>
        <%= Html.StandardOverlayCreateButton() %>
        <div class="apple_overlay" id="overlay">
            <div class="contentWrap">
            </div>
        </div>
    </asp:Content>

I have the partial view Grid:

<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<IEnumerable<UserInterface.Models.EmployeeForm>>" %>
    <div>
        <table>
           ...
        </table>
    </div>

And I have the Create page/overlay that is rendered into the contentWrap div:

<div>
        <h2>
            Create</h2>
        <% using (Ajax.BeginForm("Create", "Employee", new AjaxOptions { HttpMethod = "POST", OnComplete = "$(\"a[rel]\").close()", InsertionMode = InsertionMode.Replace, UpdateTargetId = "gridcontainer" }))
           {
        %>
        <% Html.EnableClientValidation(); %>
        <%= Html.ValidationSummary(true) %>
        <fieldset>
            <legend>Fields</legend>
           ...
        </fieldset>
        <p>
            <input type="submit" value="Create" />
        </p>
        <% } %>
</div>

EmployeeController:

//
// POST: /Employee/Create
[HttpPost]
public ActionResult Create(Employee employee, [Optional, DefaultParameterValue(0)] int teamId)
{

    employee.AddTeam(_teamRepository.GetById(teamId));
    _employeeRepository.SaveOrUpdate(employee);

    var updatedmodel = Mapper<List<Employee>, List<EmployeeForm>>(_employeeRepository.GetAllEmployeesWithEagerLoadedTeams());

    // What do I have to return here?!
    return View(updatedmodel);
}

How can I update the partial view Grid after I created the new employee without loading the whole Index page?

Thanks in advance!