The installation turned out to be a relatively painless process. Here's how I did it on Ubuntu Dapper.
First we need to install a couple of packages:
sudo apt-get install samba smbfs
I'm not positive that smbfs is required for the Samba server, but most guides recommend it. So I'll follow their lead.
A vanilla install of Ubuntu should be properly configured for Samba, so there's not much else to do besides add to the list of Samba users. In the second line, you may replace sudo with gksudo if you prefer one of the GTK editors, like gedit. There may be an analogous command for KDE apps, but I rarely run them as superuser, so I wouldn't know.
sudo smbpasswd -a system_username
sudo vi /etc/samba/smbusers
where system_username is the user you wish to add as a Samba user. You will be prompted to create a password. This is the password the user will use to connect to Samba shares.
We must add the following line to /etc/samba/smbusers:
system_username = "network username"
Note you may make the network username different from the system username. There are a variety of reasons you might do this. For example, the user may have a different name on the machine from which he will connect to the Samba shares. You might alternately designate a unique username as a security measure.
To set up your Samba shares, you must either edit /etc/samba/smb.conf by hand or install SWAT, which supposedly does the dirty work for you. Either way, the lines you add to the file should look something like this:
path = /windows/Music
browseable = yes
writeable = yes
valid users = jlz27
admin users = jlz27
I'm typing this from my PowerBook, running Mac OS X 10.4.10, while connected to one of the Samba shares. So it definitely works.