There are two simple ways in which the connection between SBS 2003 and the client PCs can be configured to connect to the Internet. One has two network cables connecting to the back of the SBS 2003 and is called a twin NIC (Network Interface Card) or duel homed solution. This has the SBS 2003 system as the controlling gateway and firewall to the Internet.
SBS 2008 only supports a configuration using a single NIC in the SBS 2003 and SBS 2008, and the firewall and router must be one or more external devices.
If you have a single NIC solution, you don't need to carry out the work of this section; however, if you do have two NICs that are in use, then you need to follow this process to change to a single NIC solution.
Install your firewall and router and ensure DHCP is turned off on these devices. You will need to refer to the device-specific manual to disable DHCP as it is normally on by default.
Physically re-configure SBS...