I should not have been surprised. Survey after survey shows that whether you measure your productivity in facts researched, alien spaceships vaporized, or articles written, adding an extra monitor will give your output a considerable boost -- 20 percent to 30 percent, according to a survey by Jon Peddie Research.

So now, while I am editing this article on my main screen, the screen beside it shows the outline or earlier draft I am working from -- and, sometimes, Web sites or other documents I keep referring to.

When I edit photos, the second screen lets me compare the copy I am working on with the original, or shows tool palettes and thumbnails of other images, and I can blow up panoramic shots for closer viewing (though with a bar down the middle, like the central pillar of an old car's windshield). When I am shopping on the Web, my two screens let me compare products. When I work on tables or spreadsheets, I can see all the columns at once. When I expect important messages, I keep my e-mail program open on the side monitor while I work on something else.

With a single monitor, I could jump between applications with a mouse click or a keyboard command (Alt-Tab, in Windows), but not nearly as fast -- and small delays add up when you repeat them dozens or even hundreds of times a day. With my dual displays, I simply sweep my mouse from one screen to the other.