Networking
Two types of networks can be used, wired and wireless. Each have their advantages and disadvantages.
Wired Networks
More Secure, others have to be "on the Network" to listened in.
Consistent performance, speed will be determined by the slowest device being used. Distance will not slow the speed (up to the limit of Ethernet wiring) .
Speed, 100Mbps devices are common and inexpensive, 1 Gbps devices are available.
Most common is Ethernet running over CAT5 cable. This has RJ45 connectors and loks like a slightly wider phone jack (8 wires vs a phone jacks 2 or 4 wires).
Wireless
Ability to move around. Laptops can be moved from room to room and stay connected.
Laptop with Wireless card can connect to the internet in "Hot Spots"
Speed decreases as distance or obstructions reduce the signal.
Others can "listen" in by using their wireless devices if the network is left unsecured. There are steps that can be taken to make the network secure.
802.11b Devices are limited to 11 Mbps and was the first wireless protocal to be widely used.
802.11g has a rated output of up to 54 Mbps and some offer speeds up to 108Mbps.
802.11a was also capabloe of speeds up to 54 Mbps, but it was never widely adopted due to its higher cost and lack of backward compatability with 802.11b devices (which 802.11g has).
802.11n has speeds over 100 Mbps and has about 2x the range of the previous standards. The main drawback to the 802.11n at the current time is that it is a draft standard. This means that different manufacturers devices may not work well with others. The "official" standsard is expected to be released in mid 2009. If you do deploy this technology, try to use all the same brand of receivers and access points.