There are two areas that I will not be discussing in the migration steps as they either impact only a few users or are too broad to cover in detail.
ISA Server is an optional component of SBS 2003 Premium Edition that provides an intelligent firewall to the system. ISA Server 2004 is found only on a small proportion of SBS 2003 systems. As the network will need a firewall that is not installed on the server, the simplest solution is to remove ISA Server 2004 from SBS 2003 before migration.
Network security and firewall settings can cause problems during migration especially if they are not configured to the standard SBS 2003 settings. For example, when writing the chapters on migration, the system I was working with had Symantec security software on that continually blocked network communications. In the end, I disabled the network security to enable the migration to continue once I was sure the existing network was...