Asp.net MVC 3 自定义错误信息

我喜欢自己自定义下错误信息，比如：添加个错误的小图标，搞错误样式。发现默认的@Html.ValidationMessage 达不到我的目标。

建立Model:

    public class Login_Index
    {
        [DisplayName("登录账号")]
        [Required(ErrorMessage = "登录账号不能为空")]
        public string user_name { set; get; }

        [DisplayName("登录密码")]
        [Required(ErrorMessage = "登录密码不能为空")]
        public string user_password { set; get; }
    }

建立HTML：

            @using (Html.BeginForm())
            {
                <fieldset class="form">
                 @Html.ValidationImage()
                    <p>
                        @Html.LabelFor(m => m.user_name)
                        @Html.TextBoxFor(m => m.user_name)
                    </p>
                    <p>
                        @Html.LabelFor(m => m.user_password)
                        @Html.TextBoxFor(m => m.user_password)
                    </p>
                    <button type="submit" class="positive" name="Submit">
                        <img src="/content/images/key.png" alt="Announcement" />登录</button>
                    <ul id="forgottenpassword">
                        <li class="boldtext">|</li>
                        <li><a href="/Login/forgot">忘记密码怎么办?</a></li>
                    </ul>
                </fieldset>
            }

Action操作：

        /// <summary>
        /// 用户登录处理
        /// </summary>
        /// <returns></returns>
        [HttpPost]
        public ActionResult Index(Login_Index model)
        {
            if (ModelState.IsValid)
                return RedirectToAction("Index", "Home");
            else
            {
                return View();
            }
        }

扩展HtmlHelper:

        /// <summary>
        /// 自定义扩展错误显示界面
        /// </summary>
        /// <param name="helper"></param>
        /// <returns></returns>
        public static MvcHtmlString ValidationImage(this HtmlHelper helper)
        {
            // 查找所有错误信息
            StringBuilder sbErrors = new StringBuilder();
            foreach (var item in helper.ViewData.ModelState.Values)
            {
                if (item.Errors.Count > 0)
                {
                    for (int i = item.Errors.Count - 1; i >= 0; i--)
                    {
                        sbErrors.AppendFormat("[{0}]", item.Errors[i].ErrorMessage);
                    }
                }
            }
            if (sbErrors.Length < 1)
                return MvcHtmlString.Empty;
            TagBuilder tag = new TagBuilder("p");
            tag.AddCssClass("error");
            tag.InnerHtml = string.Format("<img src=\"/content/images/error.png\" height=\"16px\" width=\"16px\" />{0}", sbErrors.ToString());
            return MvcHtmlString.Create(tag.ToString());
        }

显示效果：