The PC Card, a credit card-shaped device that plugs into a slot on your notebook, can provide a number of connection types--modems, USB connections (say, for your digital camcorder), and wireless WAN radios are all available in PC Card form. PC Cards are handy because they're easy to upgrade and because you can buy third-party PC Card solutions after you purchase your notebooks. However, most notebooks come with only one or two Type II PC Card slots, forcing you to limit the number of PC Cards you can add.

The Proxim Orinioco World PC Card (left) and the Netgear WAB 501 dualband wireless adapter (right) are two examples of PC Card wireless adapters with antennae that extend beyond the edge of the notebook.

ExpressCards are the next generation of the PC Card. Smaller than existing PC Cards, ExpressCards promise data transfer rates that are twice as fast, which means the cards can be used for high-bandwidth interfaces such as Gigabit Ethernet ports and HDTV tuners. The standard is still relatively new, so there aren't many ExpressCard modules on the market today. However, most current laptops include an ExpressCard slot for future use. If you know you'll want to add some of these high-bandwidth functions to your laptop after you buy it, consider a system that supports the new standard.

Though the standard is being phased out, most notebooks still come with a 56Kbps modem (RJ-11) connection, and virtually all include Ethernet (RJ-45) or even faster Gigabit Ethernet connections. Almost all notebooks also include built-in antennas for wireless networking (802.11, or Wi-Fi) so that you can access wireless hotspots. If you choose a notebook with networking built in, consider getting at least an 802.11b/g radio. Some newer models even come with the latest and fastest Wi-Fi standard to date, the 802.11n.

If your travels regularly take you beyond the reach of Wi-Fi hotspots, you might want to consider spending a little extra for a notebook with a built-in WWAN card. These systems let you tap into a cellular provider's data network. They can be incredibly useful when connectivity is spotty, but the technology has its downsides: Data plans still tend to be pricey; throughput speeds, while improving, are still slower than most high-speed Internet; and your built-in cellular card can work with only one cellular provider.

Depending on the model you choose, you may also have the option (often for an additional cost) of ordering a Bluetooth adapter in your laptop. This will let you connect your laptop to other Bluetooth-enabled devices (such as a printer, cell phone or PDA) that are in close range.

If your notebook doesn't include any of the above network adapters, it's fairly easy to find PC Cards that get the job done.

Most notebooks have a VGA port for an external monitor, Ethernet and modem jacks, headphone and microphone jacks, and two to three (or more) USB ports for connecting an external keyboard and mouse, drives, digital cameras, and MP3 players. For home use, you may want any variety of A/V connections, such as S-video, HDMI or S/PDIF output, and a FireWire port for capturing and editing digital video or hooking up an external storage drive.