...den Format-Dialog anzeigen?

procedure TForm1.Button1Click(Sender: TObject);
begin
  ShellExecute(Application.Handle,
               PChar('Open'),
               PChar('C:\Windows\Rundll32.exe'),
               PChar('Shell32.dll,SHFormatDrive'),
               PChar('C:\Windows'),
               SW_SHOWNORMAL);
end;