basic RJS question with render update

Hi-

Just trying to confirm my understanding here. In Rails 2.02, all I
have to do to fire off an RJS file is to simply name it the same as
the action (plus .js.rjs) right?

So in my view, if I have:

<%= link_to_remote "Alert", :url =>{:action => 'do_alert'} %>

and if I just create a file called do_alert.js.rjs like this:

render :update do |page|
page.alert('hello')
end

should this work? It doesn't. The log file says missing template,
and is trying to render the html.erb file for the controller.

It's not clear to me what render :update does, versus simply calling
page.alert. Anyone have a good reference to point me in the right
direction?

Thanks for any help,
Dino

Ok, please disregard myn posting, I figured out that render :update is
for use in the controller itself, not in the rjs.
Dino