Last year, Samsung released a 19" LCD monitor capable of being hooked up via a simple USB connection. To work its magic, the display uses an embedded video chip made by a company called DisplayLink that works like a sort of self-contained graphics processor. That's neat, but what if you already have a spare monitor you'd like to use via USB? Is there a cheaper alternative to coughing up the $300 or so for a USB display? As it turns out, yes there is. DisplayLink's video chip is also available in standalone USB-to-DVI adapters, which allow one to connect any monitor with a resolution up to 1600 x 1200 via USB.

The prospect connecting pretty much any display without an extra monitor port has obvious appeal, especially for laptops. USB only has a fraction of the bandwidth supported by the DVI interface, but DisplayLink nonetheless claims on its website that it's fast enough to allow "flawless DVD playback" and to enhance one's gaming experience in "most games." I was curious to put these claims to the test, so I got in touch with DisplayLink and the company graciously offered to send me a sample USB-to-DVI adapter. You won't find this exact device anywhere commercially. Instead, you'll need to look for an adapter built by one of DisplayLink's partners, such as this Sewell model that's available for $149.95. The drivers are the same, though, as should the hardware be in both adapters.

Trying the adapter in Windows XP
Since the usefulness of DisplayLink's adapter ought to be greatest to laptop users, I first tried it on my now-aging IBM ThinkPad T41 (yes, it's so old it's not Lenovo-branded). The machine has Windows XP Professional installed, and it includes a modest 1.7GHz Intel Pentium M processor coupled with a Mobility Radeon 9000 graphics processor and 512MB of RAM. Getting the adapter to work on this system was a breeze. I ran the installer, rebooted, and was good to go.

I tried three different LCD monitors—a 20.1" ViewSonic wide-screen display, a 19" LG wide-screen display, and a standard 17" LG—and they all worked flawlessly as soon as I connected them, just like they would through a DVI or VGA connection. DisplayLink allows you to configure multi-monitor settings right from Windows' built-in display control panel, although the company's own tray application provides a quicker way to change some of the same parameters, like the extra display's resolution and behavior. Everyday desktop tasks behaved smoothly, so I tried to pop in my Raiders of the Lost Ark DVD to test full-screen movie playback. The DVD played smoothly on the 17" display at 1280 x 1024, but playback on the 20.1" pegged my laptop's CPU to 100% and caused dropped frames. Normally, CPU utilization while playing a DVD on the machine's 1440 x 1050 display is quite low, so there's evidently some overhead involved with the DisplayLink adapter.