You should ban all IP's except your own from accessing wp-admin. Place this in an .htaccess file inside wp-admin folder.
Adminimize has nothing to do with WP security, it just minimizes admin area for non-admin users. You should install a plugin related to login failure.
I use Wordpress Firewall 2. It protects the blog from all sorts of attacks and send you a detailed email with the type of attack and IP address of the offender.