Registration

Hi all you clever WP people.
I would like to know a simple method of setting up a registration form for my blog page. This would simply enable visitors to comment on blog topics. Their details would need to be verified by the administrator (myself)for the site. Ideally this would be by via email, that is, visitors would fill in a form with a chosen username, password, their name and their email address. They would then receive an email back enabling them to log in to the blog.
Any help would be much appreciated.
Thanks
Mike