New User Account

Since lurking in this ng I've learned that creating a non-administrative user account
will enhance security.
How does this work?
I'm the only user and the Administrator.
If I create another account will I need to create a password for both accounts?
When my system starts will I be prompted as to which user is to log in or can
I select a user to automatically log in?
Can I delete the user account using Vista Basic?