In addition to disabling guest, check out the Security -> Logins tab in EM. There, if you right click a group or a user, you can make sure they don't have Permit access to your DBs or any server roles that grants them the ability to grant themselves access to the DB.
Catadmin - MCDBA, MCSA
"If a person is Microsoft Certified, does that mean that Microsoft pays the bills for the funny white jackets that tie in the back???