We are currently running an actiontech DSL modem for internet access. This has a public IP address. The modem is directly attached to our MS Server 2003, which acts as a Firewall and NAT with DHCP and DNS. It is also our domain controller and it 'serves' the internet for workstations. The DSL modem also has a basic firewall on it.
My boss wants to know how 'secure' we are with that set-up. Also if their are any good, cost-effective pieces of intrusion detection software for server 2003.