A wireless network adapter, or wireless network card, works the same way any cabled network adapter does. It breaks up raw data into small packets of information, and then sends these packets one at a time to their destination. On the receiving end, the network adapter does the reverse: it takes ones and zeros from the network and assembles them as they were originally sent, eventually passing them on to the computer's CPU. While a traditional network card turns the ones and zeros that make up data packets into electrical pulses and places these on a wire made of copper, a wireless card turns ones and zeros into radio signals and sends them out into the air.
Most of this lesson assumes that you already have a wireless network card installed. The steps to install such a card are really no different than installing every other piece of hardware: you plug the card adapter into the appropriate port, and then install the drivers. (Caveat: Some manufacturers instruct you to do just the reverse, so the drivers will be available when XP detects the new hardware.) But because it's such an essential part of the puzzle, let's identify the different types of wireless network adapters out there:
PCI adapters (including PCI Express). These fit into an open PCI (Peripheral Components Interconnect) or PCI-x slot on the system's motherboard, and an antenna sticks up from the back of the computer. These require you to open your computer case for installation, and cannot be used on laptops.
USB adapters. These combine the antenna and card in one piece, and are then attached (sometimes via USB cable) to an available USB port. Some advantages of USB cards include their portability and the ability to position the antenna.
PCMCIA cards. Probably the most common choice for laptops without built-in wireless cards. These credit card-sized devices are hot-swappable and very portable. Unlike some USB devices, there are no cables necessary. They can drain battery power, however, so it's recommended than you not use them unless a wireless network is present.
Integrated Adapters. On newer laptops and desktop motherboards, the wireless network card is integrated, just like the video and sound cards. You don't have to install anything at all. Intel's Centrino, for example, refers to a laptop motherboard chipset that 1) includes a wireless card, and 2) reduces battery consumption.
A Word about Bluetooth
People often confuse Bluetooth and IEEE 802.11, and with good reason. Both are wireless technologies, and both let computing devices communicate with one another
The difference is that while IEEE 802.11 is strictly a networking technologywireless cards and access points simply replace their cabled equivalentsBluetooth is a "cable replacement" technology. For example, Bluetooth might let a wireless mouse and keyboard communicate with a Bluetooth adapter attached to a computer, or it might let the computer send a print job to a Bluetooth-enabled printer. There's no 802.11 technology that does the same. 802.11 exists only to send Ethernet packetsthe kind used on virtually every wired LANthrough the air.
And a Word about Wi-Fi
And one more thing. 802.11 is not the same as Wi-Fi, although it's not uncommon to hear the words used interchangeably. Wi-Fi refers to a specific kind of 802.11 device that has been deemed "Wi-Fi Certified" by the Wi-Fi Alliance. A device earns this right by virtue of its proven interoperability with other Wi-Fi devices from different manufacturers. In other words, you can access a "Wi-Fi Certified" access point from your "Wi-Fi Certified" network card even if they are made by different manufacturers.
Does it matter? Only if you're concerned with security. In my experience, and as reported by many others, devices that aren't Wi-Fi certified work just fine, even when used on networks where all other devices are. The only real requirement is that all devices use the same radio frequency.
More about the security consideration later on in the chapter.