Locking it up further

I have a site that I don't want anyone in unless they have a password, so I am using the code below in my webconfig.
<authentication mode="Forms">
...
</authentication>
<authorization>
<deny users="?"/>
</authorization>Is it possible to lock it up even further? What I mean is.. I want to lock out adminstrative features, so I want them to log in again at a different login screen to access the admin features of the site.
...