Σε ένα μικρό demo που έφτιαξα δείχνει να παίζει.Το markup μου μέσα στην 
default2.aspx είναι αυτό εδώ
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default2.aspx.vb" Inherits="Default2" %>
 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script src="Scripts/jquery-1.4.1.js" type="text/javascript"></script>
 
 
       <script type="text/javascript">
           $(function () 
           {
               $('input[id$=Button1]').click(function (e) 
               {
                   e.preventDefault();
                   var $thelink = $('a[id$=HyperLink1]');
                   var Url = $thelink.attr('href');
                   var theUrl = "http://www.asp.net";
                    $thelink.attr('href', theUrl);
                   $thelink.text("ASP.Net");
 
              });
           });
</script>
 
 
</head>
<body>
       <form id="form1" runat="server">
       <div>
 
           <asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl="http://www.bbc.co.uk">BBC</asp:HyperLink>
           <asp:Button ID="Button1" runat="server" Text="Button" />
 
 
        </div>
       </form>
</body>
</html>
δες εδώ
http://api.jquery.com/attr/http://docs.jquery.com/Text()
Νικόλαος Καντζέλης
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