eBox 0.12.1, install it, log into the web admin page, and turn on file sharing with PDC (and roaming profiles if you want that). Add the users, and you'll be done. That was easy, wasn't it?
The eBox install disk weighs in a 560MB and is based on Ubuntu 8.04. In fact, The install is in two parts. The base Ubuntu system is installed, the system reboots, and the rest of the eBox system is installed. This kind of reminds me of the old, two-stage Debian install. Everything is on the disk so you don't need network access if you can't get hooked up.
In addition to Samba, eBox has an LDAP server. That means that eBox can serve as a bridge while you start a migration from Windows to another oprating system. Since I've never seen an easy LDAP installation, eBox seems the way to do that.
If you want a cut-down version of eBox, it can operate as a firewall and VPN system, too. Each of the modules can be deactivated or removed to trim the system down.
Still not convinced? There's a web server with user shares, a mail server with quotas, a Jabber server, a DHCP server, a print server, and a proxy server with Dansguardian.
If you are one of the few small businesses which doesn't have an actual server yet, consider using eBox.
Is it brain-dead easy? No. You'll need just as much know-how to set this up as you would getting a Windows Server PDC going and secure. Once eBox is going, you should be good for the next four years. There are no client licenses to buy or limitations on number of connections, either.
Consider it, eh, Tommy? Save me some headaches.