Web Access Rules for auhenticated and UN authenticated users

Hi all,

We're running TMG 2010 Version: 7.0.8108.200.

I´m trying to create a rule set that will:

a) Allow AUTHENTICATED users web access through a whitelist
b) Allow UNAUTHENTICATED users unrestricted web access

They're all on the same subnet.

The rule that allows UNauthenticated users is above the one for the authenticated users, otherwise UNauthenticated user are precluded from further processing.
But then I need a way to exclude authenticated  users from matching that rule.

Any ideas? I'm lost here....

Thanks!
- Kris