How to include a juery ui file in drupal 7? In my code for drupal 6 I had added the following js, jquery-ui and css files

 jquery_ui_add('ui.draggable');
  drupal_add_css(drupal_get_path('module', 'ort') . '/js/jquery.alerts.css');
  drupal_add_js(drupal_get_path('module', 'ort') . '/js/jquery.alerts.js');
  drupal_add_js(drupal_get_path('module', 'ort') . '/js/ort.js');


For drupal 7 I have to write the above code..
I have read that drupal 7 has jquery ui as part of core so how should add the

jquery_ui_add('ui.draggable'); //drupal 6


code given above in drupal 7 ?
It should be drupal_add_library('system', 'ui.draggable');