Is it safe to delete the 3 default databases created during a PostgreSQL install?

Question

I installed a default installation of PostgreSQL 8.4 on Windows 2003 Server, using the one-click installer provided. Running psql -l for the first time, I noticed there are three databases installed by default: postgres, template0, and template1.

Being security-minded, my initial reaction is to delete or change default configurations. However, I also know I haven't a clue regarding databases (as this install is my first step in self-learning about databases), so I thought I would ask first.

Is it safe to delete these?