Imagine that all the hassle associated with computer networking adapters, cables and configuration issues suddenly disappeared, and all you had to do to connect multiple PCs to each other and to the Internet was to plug their power cords into an ordinary AC wall outlet.

We haven’t reached that happy state yet. However, the networking industry has taken a step in that direction with new gear that makes what’s known as “powerline networking” a reality.

Based on a year-old specification called HomePlug, these new products turn the AC wiring already built into the walls of your home or office into a local-area data network, although you still need to add an adapter to each computer you want to connect.

And while early attempts were based on proprietary technology from small companies, HomePlug is a standard that’s been adopted by scores of vendors, including such heavyweights as Cisco Systems, Motorola and Texas Instruments. Also, the trade association behind the spec the HomePlug PowerLine Alliance certifies products based on it to ensure they work together.

If you have more than one computer at home or in the office, there are many reasons to network them to share files and printers, for example. But for most the case gets compelling when you have a high-speed Internet connection.

Remember, though, that simply linking your machines to each other doesn’t get them on the Internet for that you have to have a cable or DSL line and modem, and if you want multiple machines connected to it, you need another device called a router.

Powerline networking comes into play after you’ve got all that set up, when you want to provide fast Internet access for other computers that aren’t already wired up to the router. Eventually, Linksys and other vendors will offer routers with a HomePlug powerline connector built in, so you’ll need a separate powerline adapter only for the computer you want to connect.

Powerline’s competition

Granted, there are already several other good ways to create a home or small-office network, but powerline has some advantages over each of them

Compared with the classic approach running Ethernet cabling the big benefit of powerline is obvious: No new wires required, so no need to rip open floors or walls or to leave cables exposed. And as long as your computer has a USB port or two, you don’t even need an Ethernet adapter.

Stacked up against wireless networking, based on the hot Wi-Fi (802.11b) standard, the big difference is range. Wireless LANs normally work within a radius of 100 to 200 feet from their base station or access point, but if there’s obstruction from appliances or metal file cabinets, say the actual coverage area may be less.

HomePlug powerline gear, by contrast, is supposed to work at distances of up to 1,000 feet.

Powerline networks are also faster than Wi-Fi.

HomePlug is supposed to move data at 14 Mbps, compared with a maximum of 11 Mbps under the 802.11b standard. You won’t notice any difference when surfing the Web because both technologies offer far more bandwidth than even the fastest standard cable or DSL connection. But if you spend a lot of time moving big files around your home network say, copying MP3 files from one PC to another HomePlug will definitely cut the wait perceptibly.

In addition, powerline networking seems to be free of the security concerns that have cast a shadow over the Wi-Fi world. Passers-by outside your home can’t simply tap into an AC LAN, as they can with an unprotected wireless network.

And to protect your data from anyone who does manage to plug into your wiring, the HomePlug specification includes 56-bit DES encryption.

Wi-Fi, on the other hand, has a couple of big pluses over powerline networking: First, notebook owners can add Wi-Fi just by installing a credit card-sized PC card inside their machine. It’s not yet possible to make a HomePlug adapter that small, so the only choice is an external box. It’s not big as computer gizmos go, but it’s not something you’d want to carry around with your notebook.

Second, Wi-Fi works in appropriately equipped laptops even when they’re not plugged into an outlet. That’s a pretty compelling advantage.

Altogether, if the only machine you’re trying to network is a notebook, Wi- Fi is probably the better choice. If you want to connect two or more desktop machines plus a laptop, you can easily combine Wi-Fi and powerline networks.

Password concerns

A note to Mac users: Linksys’ USB powerline adapter doesn’t work at all with Apple hardware, but the Ethernet bridge does. Since all Macs have had Ethernet ports for years, that’s not much of a problem.

There’s just one caveat. All Linksys powerline devices ship with the same encryption password, so they can talk to each other.

If you’re concerned about the possibility of an intruder tapping into your powerline network, it makes sense to change the password, as long as you do so for all the powerline devices on your network.

To do that, you have to run a small program called the Security Configuration Utility, and that’s available only for Windows. But if you have access to even one Windows PC, you can change the password on all your powerline devices there. Then connect them back up to the Mac, and they’ll continue to work normally.