Available Features in a NAS system:

Gigabit Ethernet capability
    Did I even have 10/100/1000 byte LAN
capabilities? I
had to look it up in my motherboard manual. (The answer was yes.) Of
course my router doesn’t support it yet, but eventually my whole
network will. This opens up the possibility of serving movies on the
home network. Most NAS boxes are gigabit capable, but check those
bargains and closeouts closely. They might be on sale because of slow
network speeds.

RAID
    Some NAS systems have two bays, and the
option of
setting up a RAID. Having a mirrored (RAID 1) system means two hard
drives act as one, reducing the chances of data loss. Lose one drive,
and you only lose time rebuilding the RAID. This sounds like a great
feature for me, as I want to store and backup precious data. A RAID 0
system splits up the data across the two drives, and speeds up reading
and writing throughput, but increases the risk of data loss. Business
class systems have 4 or more bays, with all sorts of options, but that
is beyond my home network need.

Backup automation
    The various manufacturers include
 backup
software, potentially automating data archival. You may already be
using something, so it won’t matter – if the software can back up to a
network device. This also applies to the NAS – can it backup to another
network device? That would be handy if you want to be really secure.
Then you could buy a second NAS as a back up.

Heat and Noise
    These two are linked. A sealed metal box
without a
fan will be quieter, but may run hotter than a perforated metal box or
one with a fan. Some hard drives make more noise than others too.
Maxtor has a reputation for noisy drives, while Seagate and Western
Digital are supposed to be quieter.

UPnP
    Universal Plug and Play is an emerging
standard for
networked devices. If your NAS box is UPnP capable it should more
easily communicate with other PCs and non-computers on your network
with fewer configuration headaches.

USB ports
    One or two USB ports on the back of your
NAS device
allow the further addition of storage or a printer.  You need
to
read the fine print to see how usb devices are treated. Sometimes the
NAS firmware cannot share a USB drive securely.

Print servers
    I have a network capable printer
already, but this
is a nice way of creating one. Again check the reviews and product
specifications to see how well this actually works. 

Torrent clients
    If you do a lot of torrent downloads,
having a
separate system to serve your files could allow you to shut down your
main PC, saving energy.

Samba/FTP protocols
    Most products support these common file
sharing
protocols. Anything else is gravy. Some of the older systems required
you to use their proprietary protocols. Stay away.

Media serving
    While you don’t need a media server on
board your
NAS in order to share the music and use it on your PC, media server
capabilities will allow streaming to devices such as XXX.

Upgradabliity
Check the maximum storage capabilities to make sure you’re not getting
an old firmware that doesn’t support big drives. You’ll want
at
least 2T, preferably 4T computability.

3. Recommendations

Here are my conclusions, based on web research:

• Avoid cheap Chinese generics – with no name NAS systems,
  there are more compatability and hardware issues. Your time and data is
  too important.
• Get a RAID if you are planning on storing important data –
  and what data isn’t important?
• Wait a while if your primary interest is serving movies,
  becasue the hardware isn’t quite there yet.
• Save money by buying at the deflection point of hard drive
  prices. They wear out anyway.
• Check out several sites for current gear reviews. Look for
  truth
  in advertising complaints – was it really quiet, easy to configure, did
  the UPnP actually work?

To compare feature sets head to head, check out smallnetbuilder.com’s charts
page.
For specific brands, I would start with the HP MediaVault (mv2120).
It has good reliability, and feature set, easy upgradability for about
$300 with one 500GB drive. Complaints include the lack of a print
server, and difficulty swaping out the primary drive, as it contains
the operating system. (You have to get a specific utility from HP to
format a new primary drive.)

A strong second in the Netgear ReadyNAS Duo (RND2150),
which runs $400 with one 500 GB drive. It seems to be one half
generation behind the HP, with less features, but solid reliability and
speed ratings. If Netgear comes out with an updated model, it might be
my number one.

If you want to go cheap, and are prepared to fiddle a bit in
configuration, the Linksys
NAS200 is an older system that is $130
without drives. It delivers but has no gigabit ethernet and is a bit
slow in read/write tests.

Buffalo Technologies have a good reputation too, but as of this review
didn’t have a competitive product on the market.

Resources

• Smallnetbuilder.com
  has lots of info on NAS systems, including DIY builds.
• To get a sense of what middle America thinks of a product,
  I head to Amazon.com.
• To find what geeks think of a product, I head to
  tigerdirect.com, or newegg.com.
• To find the absolutly lowest prices, I head over to pricespy.com, its New Zealand equivalent.