Status Bar in Web Application

I have a working web service, but at times when processing say 500 parts, it is going to take quite a bit of time, like 2 mins or so...

How do I display a status bar or animated graphic using VS2005 with Ajax Extensions installed.

My controls are already in an ajax ready area...

Code:

---

<asp:ScriptManager ID="SM1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UP1" runat="server">
    <ContentTemplate>
        <asp:Panel ID="AP1" DefaultButton="Button1" runat="server">
        </asp:Panel>
    </ContentTemplate>
</asp:UpdatePanel>

---

Also what is the best way to search google for this..

P.S. Also, if this is a fairly complex task, maybe their are some commercial controls and links you could show me?