See Network Users for recommendations on setting up Windows users.
To setup a LAN (Local Area Network), each computer in the office should have an Ethernet port. That's the RJ-45 plug that looks like a giant telephone plug. You connect all your computers to a switch. A switch is just a small box about 6 to 12 inches big that has about 8 Ethernet ports in it, although the number varies. A switch costs about $50. If you have a router (see firewalls below), you probably already have a switch built into it which you can use.
Place the switch in a central location in the office and connect all the computers to it using Cat 5 cables (or better). You can get very long cables with plugs on each end and simply drill 2" holes in the walls with a hole saw to get from room to room. If your cables are too short, you can join two cables using a simple coupler. But try to avoid using couplers if you can. Also be sure not to coil too much Cat 5 in a pile since that creates interference. Don't kink the cables or let them get bent. If you are tacking them in place, you cannot let them get compressed. There are simple clips available which you can use to tack the cable to the walls. Make sure they are neat and nobody is kicking them or tugging on them. They should not be run very far next to power cords since the A/C causes interference. They can also be run under the building or through the ceiling. Alternatively, you can have a low-voltage contractor install the cabling out of sight using wall plates. Then, you just plug your cables into the wall plates.
See the Wireless section if you are interested in using any wireless connections.
Small offices with less than 5 computers are generally set up as a peer-to-peer network. In a larger office, you would need one of the computers to be running server software, typically Microsoft Server 2008. In a peer-to-peer network, you still designate one of the computers to be the server, but it would just be running Windows 7. Windows 7 has a built-in 20 computer limit for peer-to-peer.
After the computers are plugged together, and assuming you are not using a server, you can set up your network as follows. Right click (the lesser-used button) on My Computer and select Properties. Select the tab for Computer Name:
First of all, it is much easier to never fill in the Computer Description. That is a redundant and useless feature. Instead look just below it where it says Full Computer Name. That is the name you are interested in. Every computer on a network has a unique name. Also, all your computers should have the same Workgroup name. To change the Name or Workgroup of your computer, click Change (the Network ID button would just launch an unnecessarily confusing Wizard).
In the example above, the computer name is jordans2. Computer names are typically all caps although you can usually enter them either way. The workgroup name is WORKGROUP, and it forces you to use all caps. If you were using a server, then you would be part of a domain instead of a workgroup. WORKGROUP is a good name for the workgroup since it is so easy to remember. All computers on the network should have their workgroup set to this value. Try to pick a descriptive name for the computer name. Commonly used names are SERVER, RECEPTION, DROFFICE, BACKOFFICE, BUSOFF, OP1, OP2, a person's name, etc.
To share files on a computer so that other computers can access them, first locate a folder that you want to share. You should NEVER share your entire C: drive, since that gives viruses easy access to your system files and allows them to infect your computer. Just share important folders. You can share as many folders as you want. To share the folder, right click on it and select Sharing and Security, or Properties.
Check either both boxes, or only the first box. The Share name is typically the same name as the folder. Then click OK. After the network has a few moments to recognize the newly shared folder, you should be able to access it using the network path. For instance \\SERVER\OpenDentalData\.
To view your network computers and shared folders, click on My Network Places which is usually available on the desktop or from the Start menu. This is an example of what it might look like:
Ignore the MSN advertisement. The first two folders in the example above are shared folders on the local computer. The other two are shared folders on a different computer, as you can see either by looking at the name, or by noticing the drawing of the pipe connected to the bottom of each folder. Usually, when you open My Network Places, it will take a few moments for it to refresh. You may have to be a little bit patient while waiting for a folder you just shared to show here.
To see the other computers on your network, click View Workgroup Computers at the left, fourth from the top. You need to be able to see all the other computers that are connected. If you cannot see them, then they were not attached to the right workgroup, or there is something wrong with the way your network is set up. For instance, a cable might be unplugged.
If you are connected to the internet via a cable modem or DSL, you will need a router which acts as a firewall. Linksys makes a great line of routers for under $100. They come with very good instructions on installation. The cable from the cable modem or DSL modem is connected to the Wide Area Network (WAN) port on the router. The LAN port of the router is then connected to the switch so that all computers have access to the internet. Some routers have a built-in switch, and in this case you can plug all the computers into those ports instead of using an external switch. The router hides the LAN from outside computers, protecting you from many types of virus attacks. See the Antivirus for information on software firewalls including the new Windows XP Service Pack 2.