I'm investigating using ISA2K4 on a member server in a Small Business Server 2003 domain, instead of ISA2K on the domain controller itself. SBS 2003 Premium with ISA2K automatically disables RRAS on the domain controller and hands over the routing to ISA. Would you think RRAS should also be disabled on the domain controller with ISA2K4? The member server would have two NICs and be the only machine directly connected to the Internet. In effect, the domain controller would run as a client of the member server as far as ISA is concerned.
You are correct. The member server can be a member of the domain and be the only mulithomed device. Since its a member of the domain, you can take advantage of the full feature set provided by the Firewall client application.