I recently re-purposed an old ThinkPad R52 with 1Gig of RAM as a Network Attached Storage server for backups, using a few external USB HDDs for additional storage.
I thought I'd give FreeNAS a try, since after all.. it's Free.
I was very surprised by the features of this product based on FreeBSD Unix.
CIFS/SMB (samba)
FTP Server
NFS
TFTP
SSH
AFP
SNMP
Dynamic DNS (DDNS Client)
UPS
BitTorrent client
RSYNC
Unison
iSCSI (initiator and target)
iTunes/DAAP
HTTP Web Server
UPnP/DLNA (with transencoding)
I was able to set up the Server, SMB shares and the UPnP/DLNA services in about 30 minutes, and drop a VOB rip of a DVD on the server, update the UPnP DB.. I was able to stream the movie to two different clients at the same time. The built in profiles support XBox, PS3 and D-Link, as well as a bunch of others.
The entire OS runs from a 2 GB USB thumb drive, 1 Gig of RAM and a single core 1.8 Ghz processor... I'm using v7.x since the v8.0 does not have UPnP built in yet (will be added in the near future).
Just thought I would pass along this experience on, in the event that someone is looking for a cheap, fully-functional, NAS with a lot of free extras built in.
Home:
http://www.freenas.org/Downloads:
http://wiki.freenas.org/