Protect page and portfolio content

Hey,

I wonder if there is an easy way to protect page and portfolio entry content and make it only accessible to logged in users (subscriber and above).

I don´t need a fancy membership system and I use the “Members” plugin by Justin Tadlock for the basics. That works fine except the message that appaers for protected content if someone is not logged in simply destroys the layout of the site.

Maybe you have a reccomendation.

Cheers
Michael