检测系统是X86系统，还是X64系统

function IsWin64: Boolean;
var
  Kernel32Handle: THandle;
  IsWow64Process: function(Handle: Windows.THandle; var Res: Windows.BOOL): Windows.BOOL; stdcall;
  GetNativeSystemInfo: procedure(var lpSystemInfo: TSystemInfo); stdcall;
  isWoW64: Bool;
  SystemInfo: TSystemInfo;
const
  PROCESSOR_ARCHITECTURE_AMD64 = 9;
  PROCESSOR_ARCHITECTURE_IA64 = 6;
begin
  Kernel32Handle := GetModuleHandle('KERNEL32.DLL');
  if Kernel32Handle = 0 then
    Kernel32Handle := LoadLibrary('KERNEL32.DLL');
  if Kernel32Handle <> 0 then
  begin
    IsWOW64Process := GetProcAddress(Kernel32Handle,'IsWow64Process');
    GetNativeSystemInfo := GetProcAddress(Kernel32Handle,'GetNativeSystemInfo');
    if Assigned(IsWow64Process) then
    begin
      IsWow64Process(GetCurrentProcess,isWoW64);
      Result := isWoW64 and Assigned(GetNativeSystemInfo);
      if Result then
      begin
        GetNativeSystemInfo(SystemInfo);
        Result := (SystemInfo.wProcessorArchitecture = PROCESSOR_ARCHITECTURE_AMD64) or
          (SystemInfo.wProcessorArchitecture = PROCESSOR_ARCHITECTURE_IA64);
      end;
    end
    else Result := False;
  end
  else Result := False;
end;

*需要自己先判断是否是WINXP/2003之前的系统

function IsWOW64: BOOL;
  begin
    Result := False;
    if GetProcAddress(GetModuleHandle(kernel32), 'IsWow64Process') <> nil then
      IsWow64Process(GetCurrentProcess, Result);
  end;

这是 XE 以后的代码，表示你的 EXE 是 32位的，环境是 64 位的。
如果你的 EXE 是 64位的，就不用判断了，32位系统，无法运行。

需要注意是GetNativeSystemInfo 函数从Windows XP 开始才有， 而 IsWow64Process 函数从 Windows XP with SP2 以及 Windows Server 2003 with SP1 开始才有。 所以使用该函数的时候最好用GetProcAddress 。