uses Registry; 
 
function ProgrammOrdner(RelativPfad: Boolean): String; 
var 
  Reg: TRegistry; 
begin 
  Result := ''; 
  Reg := TRegistry.Create; 
  try 
    Reg.RootKey := HKEY_LOCAL_MACHINE; 
    if Reg.OpenKey('Software\Microsoft\Windows\CurrentVersion', False) then 
    begin 
      if RelativPfad then 
        Result := Reg.ReadString('ProgramFilesPath') 
      else 
        Result := Reg.ReadString('ProgramFilesDir'); 
    end; 
  finally 
    Reg.CloseKey; 
    Reg.Free; 
  end; 
end; 
 
procedure TForm1.Button1Click(Sender: TObject); 
begin 
  Showmessage(ProgrammOrdner(False)); 
end;