If you are still running Windows Server 2000 domain controllers then you should install MS09-018.
Vulnerabilities in Active Directory Could Allow Remote Code Execution (971055)
This security update resolves two privately reported vulnerabilities in implementations of Active Directory on Microsoft Windows 2000 Server and Windows Server 2003, and Active Directory Application Mode (ADAM) when installed on Windows XP Professional and Windows Server 2003. The more severe vulnerability could allow remote code execution. An attacker who successfully exploited this vulnerability could take complete control of an affected system remotely. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Firewall best practices and standard default firewall configurations can help protect networks from attacks that originate outside the enterprise perimeter. Best practices recommend that systems that are connected to the Internet have a minimal number of ports exposed.
MS09-018
Vulnerabilities in Active Directory Could Allow Remote Code Execution (971055)
Windows 2000 Server
Consistent exploit code is likely that can cause a denial of service condition on Windows 2000 servers that expose the LDAP or LDAPS service on the network. However, due to additional checks on the heap, a functioning remote code execution exploit is very unlikely.
Windows Server 2003
The security effect of this vulnerability is a memory leak that can eventually lead to denial of service. Code execution is not possible.