Force user to login

I’ve been looking for a way to force user to login/register. I’ve seen a few old threads, primarily http://wordpress.org/support/topic.php?id=4300#post-30774

Now, that one was for 1.2, there isn’t auth.php in 1.5

My thought is that I can use the auth_redirect() function inside wp-blog-header.php, but I was wondering if there is a better way.

The long term goal to be able to protect posts and pages based on user level So, if you are not authenticated or you are, but your level is not privileged enough, you won’t see the post from any angle (main page, any of the archive pages, and search).

thoughts?