5
There are many options available to you, one of which is a hub, as mentioned. Any computer and or laptop will work this way and this is especially true for 'typical' everyday users.
You can get a hub for reletively low cost. Essentially, all you do is plug the netwrk cable from your modem (assuming your on broadband of some sort here) to the hub. Then plug each of your computers into the hub. If your on WindowxXP, just run the network wizard and let it take care of things for you.
Thats the quick and simple solution with little details.
You could also go get a switch, or a router which works under the same principle, but also acts as a firewall.
No matter what your solution, your best bet is to go to
http://www.linksys.com There you will find may FAQ's and will be able to make an informed decision on which hardware type you should purchase.
Thats just my reccomendation, other opinions will vary but the principals and goals are the same.