It shouldn't be letting you chose older versions if you are upgrading from 1.4.1

There should be a file in the 'config' folder called 'installed_version.php' that should contain this (if you have version 1.4.1):
<?php
/**
* Some comments ...
*/
return '1.4.1';
?>
If you don't have this file or it has different contents, try manually creating the file and try upgrading again.
Running the upgrade is not too important. Only one query is executed that will enable the calendar config options because they weren't enabled on some versions. This is the query:
UPDATE `og_user_ws_config_categories` SET `is_system` = 0 WHERE `name` = 'calendar_panel';
You may have to change the table prefix from 'og_' to something else if you entered another one during installation.