[san-46]

А так:

Код:

type
  TMemoryStatusEx = record
    dwLength: DWORD;
    dwMemoryLoad: DWORD;
    ullTotalPhys: Int64;
    ullAvailPhys: Int64;
    ullTotalPageFile: Int64;
    ullAvailPageFile: Int64;
    ullTotalVirtual: Int64;
    ullAvailVirtual: Int64;
    ullAvailExtendedVirtual: Int64;
  end;

  procedure GlobalMemoryStatusEx(var lpBuffer:TMemoryStatusEx); stdcall; 
                    external kernel32 name 'GlobalMemoryStatusEx';

var
  memStatus: TMemoryStatusEx;

procedure TForm1.Button1Click(Sender: TObject);
begin
  memStatus.dwLength := SizeOf(TMemoryStatusEx);
  GlobalMemoryStatusEx(memStatus);
  Label1.Caption := FloatToStr(memStatus.ullTotalPhys);
end;

У меня работает.