Shas3 is correct. Consider that as far as SQL Server is concerned - SA is GOD. GOD can do anything, you can not stop GOD. But you CAN stop other people/users from pretending to be GOD. Put a strong password on the SA account and don't share it with those who don't need it. Remove the Builtin/Administrator account after testing to ensure that nothing uses it. That account allows anyone who is Administrator for the Operating System to also be Administrator for the SQL Server. Don't put anyone in the SysAdmin Role unless they really require it. Since you appear to be the database administrator, you should be in this Role and not be using the SA account. Also, don't give anyone db_databasebackup privileges unless they really need it.

-SQLBill