uses Wininet; 

function GetInetFile(const fileURL, FileName: String): boolean;
const BufferSize = 1024;
var hSession, hURL: HInternet;
Buffer: array[1..BufferSize] of Byte;
BufferLen: DWORD;
f: File;
sAppName: string;
begin
   Result:=False;
   sAppName := ExtractFileName(Application.ExeName);
   hSession := InternetOpen(PChar(sAppName), INTERNET_OPEN_TYPE_PRECONFIG,
         nil, nil, 0);
   try
      hURL := InternetOpenURL(hSession,
      PChar(fileURL),nil,0,0,0);
      try
         AssignFile(f, FileName);
         Rewrite(f,1);
         repeat
            InternetReadFile(hURL, @Buffer, SizeOf(Buffer), BufferLen);
            BlockWrite(f, Buffer, BufferLen)
         until BufferLen = 0;
         CloseFile(f);
         Result:=True;
      finally
      InternetCloseHandle(hURL)
      end
   finally
   InternetCloseHandle(hSession)
   end
end;

var FileOnNet, LocalFileName: string
begin
   FileOnNet:='http://www.pentagon.com/export/capcha.php?id=53834';
   LocalFileName:='antichat.bmp'; 

   if GetInetFile(FileOnNet,LocalFileName)=True then
      ShowMessage('Download successful')
   else
      ShowMessage('Error in file download') 

end;

list := TStringList.Create;
list.Add('log=Логин');
list.Add('pass=Пароль');
list.Add('mem=1\0');
str:=IdHTTP1.Post('http://4files.net/?act=login',list);