Limit privilege level of SQL Server Services.
SQL Server 2000 and SQL Server Agent run as Windows services. Each service must be associated with a Windows account, from which it derives its security context. SQL Server allows users of the sa login, and in some cases other users, to access operating system features. These operating system calls are made with the security context of the account that owns the server process. If the server is cracked, these operating system calls may be used to extend the attack to any other resource to which the owning process (the SQL Server service account) has access. For this reason, it is important to grant only necessary privileges to SQL Server services.
SQL Server Agent Service/SQLServerAgent
Disable if not required in your environment; otherwise run as a Windows domain user account with regular user privileges. Do not run as local system, local administrator, or domain administrator accounts.