U can change the wp-admin to whatever U want by using the plugin http://wordpress.org/extend/plugins/lockdown-wp-admin/
After installation and activate the plugin, U will see a Lockdown WP menu is added to the admin side bar.Click Lockdown WP. Then U will get an option Hide WP Admin. There is a check box below it.Check the Box.
There is another option WordPress Login URL. Beside this U will see input box.Insert your desired admin folder name in that input box.
At last press the save option button then logout from the admin panel.