ctools

gistfile1.aw

$form['profile-status'] = array(
      '#type' => 'radios',
      '#title' => '',
      '#options' => array(
        'new' => t('Create a new profile.'),
        'select' => t('Use an existing profile.'),
      ),
    );

    $form['select'] = array(
      '#type' => 'select',
      '#title' => t('Select a profile'),
      '#options' => $options,
      '#process' => array('ctools_dependent_process'),
      '#dependency' => array('radio:profile-status' => array('select')),
    );

    $form['profile-properties'] = array(
      '#type' => 'fieldset',
      '#title' => t('View the profile'),
      '#process' => array('ctools_dependent_process'),
      '#dependency' => array('radio:profile-status' => array('select')),
      '#input' => true,
    );