Узнать версию Windows и DOS

procedure TForm1.Button1Click(Sender: TObject);
var
  WinVersion, DosVersion: Word;
begin
  WinVersion := GetVersion and $0000FFFF;
  DosVersion := GetVersion shr 16;
  Label1.Caption:=IntToStr(Hi(DosVersion))+'.'+IntToStr(Lo(DosVersion));
  Label2.Caption:=IntToStr(Lo(WinVersion))+'.'+IntToStr(Hi(WinVersion));
end;