Full Site Authentication

Hi,

I would like to develop a social networking style wordpress website.

On the landing page I would like to have a small explanation of what the site is about as well as a login dialogue which already registered users can use to login to grant them access to the rest of the front end (which will be restricted to all non-registered users) as well as the back end of the site, (e.g profile etc).

As for the rest of the site, I would like to make it inaccessible to non-registered users, but rather display a message saying : Restricted access etc… if they attempt to click on those pages.

Is this possible?

I am currently using the arclite template and would like to continue using this template for the landing page.

Alex