//声明:
GetVersionEx(
  var lpVersionInformation: TOSVersionInfo {参数是一个结构}
): BOOL;						

//结构 TOSVersionInfo 是 _OSVERSIONINFOA 的重命名
_OSVERSIONINFOA = record
  dwOSVersionInfoSize: DWORD;              {结构大小}
  dwMajorVersion: DWORD;                   {主编号}
  dwMinorVersion: DWORD;                   {次编号}
  dwBuildNumber: DWORD;                    {建立编号}
  dwPlatformId: DWORD;                     {作业平台}
  szCSDVersion: array[0..127] of AnsiChar; {更多说明}
end;

{另外参数4(作业平台)可能的取值是:
  VER_PLATFORM_WIN32s = 0;
  VER_PLATFORM_WIN32_WINDOWS = 1;
  VER_PLATFORM_WIN32_NT = 2;
  VER_PLATFORM_WIN32_CE = 3;
  
  我没装 Vista.
}


//举例:
var
  OsInfo: TOSVersionInfo;
const
  s = '主编号: %d' + sLineBreak +
      '次编号: %d' + sLineBreak +
      '建立编号: %d' + sLineBreak +
      '作业平台: %d' + sLineBreak +
      '更多说明: %s';
begin
  OsInfo.dwOSVersionInfoSize := SizeOf(TOSVersionInfo); {先根据大小要内存}

  GetVersionEx(OsInfo);
  ShowMessage(Format(s, [OsInfo.dwMajorVersion,
                         OsInfo.dwMinorVersion,
                         OsInfo.dwBuildNumber,
                         OsInfo.dwPlatformId,
                         OsInfo.szCSDVersion]));
end;

//效果图: