C#下判断当前操作系统代码

 /// <summary>
        /// 判断当前操作系统是否允许执行该程序
        /// </summary>
        /// <returns></returns>
        public string InUserOS()
        {
            string Str_InAva = "NO";
            string str_OS = "";
            OperatingSystem os = Environment.OSVersion;
            switch (os.Platform)
            {
                case PlatformID.Win32Windows:
                    switch (os.Version.Minor)
                    {
                        case 0:
                            str_OS = "Windows 95";
                            break;
                        case 10:
                            if (os.Version.Revision.ToString() == "2222A ")
                                str_OS = "Windows 98 第二版 ";
                            else
                                str_OS = "Windows 98 ";
                            break;
                        case 90:
                            str_OS = "Windows Me ";
                            break;
                    }
                    break;
                case PlatformID.Win32NT:
                    switch (os.Version.Major)
                    {
                        case 3:
                            str_OS = "Windows NT 3.51 ";
                            break;
                        case 4:
                            str_OS = "Windows NT 4.0 ";
                            break;
                        case 5:
                            switch (os.Version.Minor)
                            {
                                case 0:
                                    str_OS = "Windows 2000";
                                    break;
                                case 1:
                                    str_OS = "Windows XP";
                                    break;
                                case 2:
                                    str_OS = "Windows 2003";
                                    break;
                            }
                            break;
                        case 6:
                            switch (os.Version.Minor)
                            {
                                case 0:
                                    str_OS = "Windows Vista";
                                    break;
                                case 1:
                                    str_OS = "Windows 7";
                                    break;
                            }
                            break;
                    }
                    break;
            }
            if (str_OS=="Windows Vista" || str_OS=="Windows 7")
            {
                Str_InAva = "OK";
            }
            return Str_InAva;
        }