We run a small consultancy with the following IT enviornment:
LAN, Mac OS X workstations, Mac OS X Sever
Is there a computer naming convenention for such a set up? For
example, should we use the hardware address, serial number, user id?
The computer name needs to be different than user name.

Hi there!

I've searched on [ "LAN setup" names ], [ LAN "computer name" ], and [
name LAN computer ], and haven't found any specific protocols for
naming one's computers on a LAN.  Based on this, and on personal
experiences, I think it's safe to say that you can name your computers
anything you want.

If you want to maintain strictly professional IDs for the computers,
you can use non-descript identifiers such as Workstation 1,
Workstation 2, etc.  You don't need to keep the names of your
computers boring and non-descript, though.  You can add a bit of
whimsy to your network and make the computers more easily
identifiable.

A few examples:

-- A local computer shop I frequent has named computers on their LAN
according to local park names - pearson.theirdomain.com,
wildwood.theirdomain.com, secor.theirdomain.com

-- The University of California at Berkeley's Open Computing Facility
maintains computers named War, Famine and Pestilence.  Those are just
three that have shown up in my e-mail headers in recent weeks.
(Today's came from pestilence.ocf.berkeley.edu  I read headers in
e-mail, and that one nearly caused a split side!)  Other computer
names on Berkelely's network include Socrates and Aristotle!

-- A friend who *used to* maintain the LAN for a small business in his
hometown in Northeastern Ohio renamed every computer on his employer's
network to a swear word just after he received his dismissal notice. 
It took a week for them to notice that e-mail from the boss's computer
generated the Received From header of f***head.thatdomain.com!

-- I maintain a small (3 node) LAN at home, and we've named our
computers according to who they belong to - Missy for my machine,
Monsters for the children's machine, and Maus for my husband's.  This
has the hilarious effect of e-mail sent from my children's computer
bearing the Received From header of monsters.mydomain.com (where my
domain is a somewhat sinister sounding name!).  I'm told it's
appropriate for them.

If the primary user of each machine has a nickname, you can use the
nickname as the machine name.  If you're an engineering consultancy,
you can name each computer for a well known engineer.  Perhaps you're
interested in Greek mythology?  athena.yourdomain.com,
zeus.yourdomain.com, hephaestus.yourdomain.com ?  The possibilites are
endless!

(Whatever you choose to name your machines, keep in mind that
communications sent out by those machines will bear the name of the
machine in the origination headers!)

Have fun naming your computers!  If you choose a theme, I hope you'll
come back and tell us some of the names you've chosen!

--Missy

When installing a LAN the computer name should help the administrator
of the lan service the network.
Names should evoque things that are useful to the users and
administrators.
But the convention itself does not follow any preconceived standards.
The name can't have spaces.
In some OS names must all uppercase.
Names can't have reserved characters (/&#.)

The name itself can be anything and there is no convention I know.
Useful data for administrators:
Location. example: states, country, building no.
Role. example: gateways, file servers, personal computer
IP. example: 003211 (last 2 octets)

Thus if I have a personal in the 2nd floor of the office and happens
to be a personal System (belongs to dana) with an IP 150.191.4.65
A good could be: dana004065

Some admins put emphasis in the OS or architecture of the system when
naming
a computer and again is up to the admin to decide what is truly
relevant
when naming a system and what is not.
Let's not forget. The computer name is a unique identifier with 2
roles and
compulsive and one optional:
1. Differentiate the system from others
2. Provide some information about the system itself (optional).

Notice.. none of this answer adresses the issue of naming a network.
cabazorro.