I want to create a network with 3 computers, only to share files, not for the internet. Will they ne

The computers will be connected across a building the size of a small school. What kind of network is that LAN or TAN? and also...what kind of cable should i use? ethernet, coaxial with what kind of connecter RJ45??? PLEASE ANSWER.

I want to create a network with 3 computers, only to share files, not for the internet. Will they need modems?computer repair

Unless you plan to run cables through the wall between the computers, or have existing CAT5 (Ethernet) wiring in place; I would setup a wireless router in the center of the building and get either PCI Wireless cards or USB Wireless Ethernet adapters.

If you have existing Ethernet wiring, you would need a hub or switch and CAT5 (Ethernet) cabling as well as a NIC (Ethernet card) in each machine.

Using a modem would require a dedicated phone line for each machine, and they could only connect (at very slow speeds) to 1 other machine at a time.

I want to create a network with 3 computers, only to share files, not for the internet. Will they need modems?free antivirus

The easiest way will be to run the systems through a hub using RJ45 connections. This way would be the easiest and the cheapest. If you every think that the systems would need to connect to the internet then installing wireless cards and using a wireless router would probably be your best bet. Although more expensive, this option will give you the most flexability.
How far apart would the computers be?
Easiest way is with a wireless router. Then you would need wireless cards on each computer. The router will come with instructions on set up etc etc.
Jordan has the right idea, while a RJ45 wired LAN would give you faster speeds to transfer data between the computers, it doesnt make sense for the distance you have to travel.
I think a wireless setup would be the best. You will need to have a modem to connect to the Internet. Then connect your modem to a router--a wireless one. Then put wireless ethernet cards in your computers. It should work fine.

And the DVD that comes with the router should have all the instructions you need. Setting this stuff up is all pretty painless nowadays---it seems like all you have to do is answer a few questions and the software takes care of the rest.
The easiest way is to create a network with a switch ( 4 or 8 port for your condition),it's the cheapest way , buy a switch and 3 fast Ethernet card and enough CAT 5 wire with rj45 jacks , you can have at least 100 mbps to 1 Gbps with this way , in wireless network you can have 54 mbps ,for file sharing 1 Gbps is actually better