Saving the module configuration form data
The form elements saved above will all be stored in the variables table. 

Are you wanting to move this data or store it somewhere else? If not, then your answer is already in your code with the variable_get() default value.

system_settings_form()


  Add default buttons to a form and set its prefix.


System settings form will store your form data in the variables table and key it with the name of the form element.  For example, a form element defined as $form['foo'] will be retrievable by using variable_get('foo', NULL).  Because of this I always figure it's a good idea to namespace your form elements as you would functions (i.e. $form['mymodule_foo'])