Check userName availability

This code used for check the user name avilability for registering from data base. This code using Ajax concept for display of available message.

<td class="whiterow" >                                                    
                                                    <asp:UpdatePanel runat="server" ID="up1" >
                                                    <ContentTemplate> 
                                                    <table>
                                                        <tr>
                                                            <td><asp:TextBox ID="txtUsername" AutoPostBack="true" OnTextChanged="Username_Changed" runat="server" CssClass="fontgnrl" ></asp:TextBox>
                                                            </td>
                                                            <td><div  runat="server" id="UserAvailability"></div>
                                                            </td>
                                                        </tr>
                                                    </table>
                                                    
                                                        
                                                        
                                                       
                                                    </ContentTemplate>
                                                    </asp:UpdatePanel>  
                                                                                                        
                                                            
                                                                                                    
                                                </td>
<tr>
                                                <td height="25px" class="whiterow" align="center" colspan="3">
                                                      <asp:UpdatePanel runat="server" id="upSave" >
                                                        <ContentTemplate>                                                     
                                                            <asp:Button ID="btnProfileSave" runat="server" Text="Save" CssClass="btnsml" OnClick="btnProfileSave_Click" >
                                                            </asp:Button>
                                                        </ContentTemplate>
                                                    </asp:UpdatePanel> 
                                                    </td>
                                            </tr>

protected void Username_Changed(object sender, EventArgs e)
    {
        String UserName;
        UserName = txtUsername.Text;  
        SqlParameter[] Params = new SqlParameter[1];

        Params[0] = new SqlParameter("@UserName", SqlDbType.NVarChar );
        Params[0].Value = UserName;

        Int32 result =Convert.ToInt32(SqlDALHelper.ExecuteScalar("USP_UserNameAvailability", Params));  

        System.Threading.Thread.Sleep(2000);

        //if (Membership.GetUser(txtUsername.Text) = 0)
        if(result>0)
        {
            UserAvailability.InnerText = "Username taken, sorry.";
            UserAvailability.Attributes.Add("class", "taken");
            btnProfileSave.Enabled = false;
        }
        else
        {
            UserAvailability.InnerText = "Username available!";
            UserAvailability.Attributes.Add("class", "available");
            btnProfileSave.Enabled = true;
        }
    }