How to use link_to for an external reference?

Suppose I wish to have the following link embedded in one of my
views.

<p><a href="http://www.rubyonrails.org" target="_blank">Ruby on Rails</

</p>

How can I use the 'link_to' method to generate an external link in
an .erb file? I have tried various options, but keep getting routing
errors.

<%= link_to 'Ruby on Rails', 'http://www.rubyonrails.org', :target => '_blank' %>

-philip

Thanks Philip, that syntax had eluded me. So simple.