How to set up Ubuntu Server as a NAS?

I just finished doing this myself and I did it using Samba. I'm able to mount the samba shares from my windows & ubuntu computers

Here are some links that helped me get started:

https://help.ubuntu.com/community/SettingUpSamba

http://ubuntuforums.org/showthread.php?t=280473

Simples:

1. Install Ubuntu Server. Really helps if you can have the server with a keyboard and monitor for this bit... Although you can script a CD to auto-install if you want. More trouble than it's worth if you ask me.

2. Create a user, set up ssh (sudo apt-get install openssh-server), etc. Put your server in its final resting place and ssh in from your desktop.

3. Install & configure samba (see the manual configuration section)

4. Optionally install NFS for linux clients (faster, less taxing on the server CPU in my experience)

5. Relax. You're done.

For the filesystem, I have software RAID 5 across my drives, and encrypt the resulting filesystem. This way, I can use this system as a backup server as well.

Once the system is up, I use plain ol' NFS and Samba for the file level access. (apt-get install nfs-kernel-server samba). I also have a PS3 that I like to stream media to, so I use mediatomb for that (apt-get install mediatomb), and my wife uses iTunes on her Mac and netbook, so I also install mt-daapd (apt-get install mt-daapd) to share my music over the daap protocol, which rhythmbox can also use.