As you noted, the dual 19-inch monitor option can be less expensive up front, but a number of hidden costs are associated with a dual-monitor setup. Many older PCs have only one VGA output; if you choose to go with two separate monitors, you may have to invest in a dual-output graphics card, which can run from $60 to hundreds of dollars. Also, depending on the manufacturer, you'll have to shell out twice for extras such as extended warranties and cables, if they're not included.

For work tasks, dual monitors are more flexible: they allow you to clone screens, putting the same images on each monitor; span the screens to create a single, large image; or use each monitor with a different resolution. With a dual-monitor setup, you can adjust image and ergonomic settings for each unit, and two 19-inch monitors offer more screen real estate than a lone 24-inch LCD.

In addition to programming, design, and photo editing, do you ever use your computer for entertainment? For watching movies and playing games, a single wide-screen monitor usually works best; with dual monitors, you have to switch to single-screen viewing, since most games and video players won't span the screens.

For most users, I recommend a single wide-screen LCD monitor. A 24-inch wide-screen LCD offers plenty of screen real estate for tiling windows and is great for entertainment purposes. A single wide-screen monitor keeps your desk less cluttered and eliminates the potential double costs of a two-monitor setup. If you do decide to go with dual monitors, check out our Weekend Project: Add a second monitor to your PC, which gives step-by-step instructions on how to make a two-monitor setup work for you.