SBS 2008 is a 64-bit operating system that requires 64-bit hardware and plenty of memory. SBS 2003 is a 32-bit operating system and there is no supported mechanism to perform an in-place upgrade from a 32-bit Windows Server to a 64-Bit Windows Server. Instead, a migration from one server to another must occur.
While this can be performed in such a way that the existing server becomes the SBS 2008 server, this adds a great deal of complexity to the migration process. The steps to achieve migration of SBS 2003 to SBS 2008 in this complex scenario are still almost the same. So, these chapters will help should you choose to re-use the SBS 2003 server as your SBS 2008 server.
Once the migration process is finished, you will have to turn off the SBS 2003 server as SBS 2003 and SBS 2008 cannot both exist on the network for more than 21 days without the occurrence of significant errors.
You can add other Windows Servers onto the network, which includes converting...