Read Restrictions

Anyone know if there’s a way of restricting un-registered users from ‘Reading’ EVERYTHING on a wordpress 2.2 unless they sign up / sign in.
The only option I could find was to restrick search engines.
So basically, to wrap up, what I’m trying to do is make it so when people land on my wordpress they are basically told ‘Register’ or ‘Log in’ and given no access to articles until they do so. Is this possiable.
Appreciate any help anyone can offer.
Cheers.