Altering user accts. in a gifted MacBook Pro

My son received a MacBook Pro running Snow Leopard from his father-in-law, who punted a PC to Mac transition. He phoned me and asked how to set up a user account. After telling telling him to obtain the administrator password, I became befuddled about what he should do. Should he just add an admin account account under his name and delete the original account. I'm afraid he may lose access to applications installed previously if they were not installed "for all users." The more I think about this, the less I seem to know.

It seems as though it would be better to change title to the machine, as it were, for support, etc. But I'm not sure how to do this.

Thanks in advance,

Gray Johnston