Thought I'd point out that John Terptstra's Samba by Example book is now available in PDF format at the samba site. This provides examples, step by step info on configuring Samba in several situations, from starting with a very small network, and moving up to using LDAP replicas for multi-site authentication using Samba.
http://us3.samba.org/samba/docs/Samba-Guide.pdf