Network for small office

this is an inexpensive easy way.
you can go an buy server 2003, setup a domain, create some gpo's, setup an onsite and offsite backup,

or you can look at clarkconnect, perfect all in one solution for a small office. setup samba for file sharing, all you firewall needs, easy backup solution. the price is a 1/20 of a   windows server. super easy to setup , alot of online material for step by step directions. all you need is cheap pc,  setup a raid 1 with a promise sata raid controller ($65 from newegg).

Here's the problem - darkconnect is not a common system.  If you know linux WELL, then setup a Linux server for yourself.  But if you are NOT an expert on Linux, then going with a linux solution is the more expensive option.  Sure, the OS is free... but the administrative costs and time involved will EASILY eclipse the cost savings on software licensing.

What I would suggest you do is buy a Small Business Server 2003 Standard Edition system.  OEM from Dell, this can be as little as $350 for the software (though honestly, I would spend double and buy a Volume License version with Software Assurance so you can get the next version (due in a few months) at no additional charge AND you have the right to use the software on a DIFFERENT server (it's not tied to the system it was sold with as OEM software is).

For the server, I recommend, ANY SERVER system with 4 GB of RAM (Any CPU to start), 2x identical hard drives in a Hardware Mirror, purchased from a major vendor like Dell, and a 3 year 24x7 warranty with 4 hour on-site service (this server IS running the business - which means you should be treating it like the workstations can fail but the server needs to be available ALWAYS and if there's a problem, you need to be able to get it fixed ASAP.  Yes, the warranty can be expensive, but it's insurance.

For backup, please review www.lwcomputing.com/tips/static/backup.asp

i recommended clarkconnect because he has linux networking under "zones"

I've given you the guidelines.  Do you need lots of storage space?  Will you need lots of storage space?  

I just setup a server for a new client with 3 workstations - just like you.  Total cost, INCLUDING all licensed software and a tape backup drive (as they need to archive for 6+ years) was $8500.  Less the tape backup drive, it was about $6500.  The workstations were all Optiplex 330 systems that were pretty basic but came with XP Pro instead of Vista and had 19" LCD screens.  1 GB of RAM to start and Office.

The server was a Dell 1900 system CAPABLE of 2 CPUs, but only equipped with the lowest end dual core processor compatible with the system.  I loaded it with 4 GB of RAM and bought the 3 year 24x7 with 4 hour response warranty.  It will support 6 hard drives internally, but I only got 2 750 GB drives for mirroring with a hardware RAID controller.