获取操作系统版本Asp.Net

/// <summary>
        /// 获取操作系统版本号
        /// </summary>
        /// <returns></returns>
        public static string GetOSVersion()
        {
            //UserAgent
            var userAgent = HttpContext.Current.Request.ServerVariables["HTTP_USER_AGENT"];

            var osVersion = "未知";

            if (userAgent.Contains("NT 6.1"))
            {
                osVersion = "Windows 7";
            }
            else if (userAgent.Contains("NT 6.0"))
            {
                osVersion = "Windows Vista/Server 2008";
            }
            else if (userAgent.Contains("NT 5.2"))
            {
                osVersion = "Windows Server 2003";
            }
            else if (userAgent.Contains("NT 5.1"))
            {
                osVersion = "Windows XP";
            }
            else if (userAgent.Contains("NT 5"))
            {
                osVersion = "Windows 2000";
            }
            else if (userAgent.Contains("NT 4"))
            {
                osVersion = "Windows NT4";
            }
            else if (userAgent.Contains("Me"))
            {
                osVersion = "Windows Me";
            }
            "))
            {
                osVersion = "Windows 98";
            }
            "))
            {
                osVersion = "Windows 95";
            }
            else if (userAgent.Contains("Mac"))
            {
                osVersion = "Mac";
            }
            else if (userAgent.Contains("Unix"))
            {
                osVersion = "UNIX";
            }
            else if (userAgent.Contains("Linux"))
            {
                osVersion = "Linux";
            }
            else if (userAgent.Contains("SunOS"))
            {
                osVersion = "SunOS";
            }
            return osVersion;
        }