Blog Notifier

I want to have a blog notifier on my side panel so like.. whenever I write a new blog entry, whoever subscribes, they’ll get an email, informing them that I’ve updated etc..
Where can I get one of these for my website? An example is on http://www.malvagita.blogdrive.com that’s my old blog but now since I found wordpress, I’m learning about stuff on here but this notifier thing is annoying me >__>
Look on the side panel on at the website I provided you, scroll down on the *right* hand side and it says ” If you want to be updated on this weblog Enter your email here” and then there’s a text box and blah blah..
Do you get what I mean?
Well thanks!! ^^;