problems with user rights

Hello,
i've just added a new user called xxx :

create user xxx with password zzz;

now am creating it's database :

create database db_xxx with owner xxx;

it works fine althought when logging with the user xxx i can still
view other databases contents  especially pg_catalog schems.

is it the right way to add a user ? am i wrong ?
i dont want to let my new user view the others databases on the server.