Автор: http://www.swissdelphicenter.ch

procedure TForm1.FormCreate(Sender: TObject);
 var
   devmode: TDEVMODE;
   d: Integer;
   litem: TListItem;
   p: ^TDevmode;
 begin
   devmode.dmSize := SizeOf(TDevMode);
   devmode.dmDriverExtra := 0;
   d := 0;
   ListView1.Columns[0].Width := 400;
   while EnumDisplaySettings(nil, d, devmode) do
     with devmode do
     begin
       Inc(d);
       litem := ListView1.Items.Add;
       litem.Caption := Format('Mode %3d : %dx%d, %d Colors   (%d Hz)',
         [d, dmPelsWidth, dmPelsHeight, 1 shl (dmBitsPerPel), dmDisplayFrequency]);
       New(p);
       p^ := Devmode;
       litem.Data := p;
     end;
 end;

 procedure TForm1.BitBtn1Click(Sender: TObject);
 begin
   ChangeDisplaySettings(TDevmode(ListView1.Selected.Data^), 0);
 end;