Howtoforge has made a little how-to on getting Samba to run for small workgroups With Ubuntu.
Read the tutorial yourself…..
This is a detailed description about the steps to set up a Ubuntu based server (Ubuntu 5.10 – Breezy Badger) to act as file- and print server for Windows ™ workstations in small workgroups. This howto uses the tdb backend for SAMBA to store passwords and account information. This is suitable for workgroups for up to 250 users and is easier to setup than an LDAP backend. A second howto covering the installation of LDAP + SAMBA will be published on HowtoForge soon.