#toolbar
    {
        position:relative;
        top: 0;
        height: 50px;
        background-color: #F4A83D;
        width: 100%;
        text-align: center;
        display: hidden;
    }

<div id="toolbar">
        TestApp ToolBar
        <br />
        You are visiting:
        <%=ViewData["url"] %>
    </div>

<script src="../../Scripts/jquery-1.3.2-vsdoc.js" type="text/javascript"></script>
   <script type="text/javascript">
        $(document).ready(function() {
            $("#toolbar").fadeIn("slow");
        });
    </script>

<div id="toolbar" style="visibility: hidden">
        TestApp ToolBar
        <br />
        You are visiting:
        <%=ViewData["url"] %>
    </div>

$('#toolbar').hide().fadeIn('slow');

<div id="toolbar" style="visibility: hidden">...</div>

$('#toolbar')
    .css({
        visibility: "visible",
        opacity: 0
    })
    .fadeIn('slow')
;

<script src="../../Scripts/jquery-1.3.2-vsdoc.js" type="text/javascript"></

<script src="../../Scripts/jquery-1.3.2.js" type="text/javascript">

display: hidden;

Visibility: hidden;

$("#toolbar").css("display","none");

$("#toolbar").css("display","block").fadeIn('slow');

display: block;

var state = $("#ex").css("display");

if(state == "none")
{
...
}
else
...

$("button").click(function() {
  $(".element")
  .css({ opacity:0, visibility:"visible" })
  .animate({ opacity:1 }, "slow");
});