Resoluçao de video

  if (Screen.Width = 800) and (Screen.Height = 600) then
   begin
     Showmessage(´tem resoluçao 800x600´);
   end;

function TrocaResolucao(X, Y: word): Boolean;
var lpDevMode: TDeviceMode;
begin
  Result := False;
  if EnumDisplaySettings(nil, 0, lpDevMode) then
   begin
     lpDevMode.dmFields := DM_PELSWIDTH Or DM_PELSHEIGHT;
     lpDevMode.dmPelsWidth := X;
     lpDevMode.dmPelsHeight:= Y;
     Result := ChangeDisplaySettings(lpDevMode, 0) = DISP_CHANGE_SUCCESSFUL;
   end;
end;