Here are some SBS Migration Articles:
How to install Small Business Server 2003 in an existing Active Directory domain Migrating SBS 2000 Server to New SBS 2000 Server What do I need to do to prepare my Windows 2000 forest for the installation of the first Windows Server 2003 DC?What do I need to do to make sure Exchange 2000 runs fine on my Windows Server 2003 forest?Using Ntdsutil.exe to transfer or seize FSMO roles to a domain controller.How to remove data in Active Directory after an unsuccessful domain controller demotion.Domain controllers do not demote gracefully when you use the Active Directory Installation Wizard to force demotion in Windows Server 2003 and in Windows 2000 Server.