Create a View of type Users
(and NOT Node
like it usually is). Now add a filter. Choose the Users
group in the filters drop down. Choose User: Roles
filter. Set the operator to is none of
and select editor, corrector etc. check boxes. This way you will ONLY see registered users on your site.
(BTW you can always expose this filter to have control on what roles you want to see/not want to see listed)
Additional Question: How to count users
Enable the PHP Filter module, add the following in the header of the view (with input format selected as PHP Filter) and insert the following code:
<?php
$view = views_get_current_view();
print count($view->result)." Users";
?>