Amid increasing reports from computer makers that desktop sales are falling in the U.S. while laptop sales are rising, Microsoft announced this week at the Computex trade show in Taiwan that it is now extending the lifespan of Windows XP on low-end desktops until 2010, which it had already done for laptops earlier this year.

The announcement indicated, according to The New York Times, that the new rule is intended to apply to limited-use desktops (or nettops, if you like ... and I don't) like the Asus Eee. Details on how Redmond will enforce that limitation and keep computer sellers from also offering XP on full-featured desktops aren't yet available.

Worldwide demand for desktops and nettops, contrary to demand shifts to mobile devices in the U.S., is rising. Leader HP, for example, saw an almost 11 percent increase year-over-year for worldwide desktop sales for the last quarter of 2007. Products like the Asus Eee box and the Atom Aspire are attracting attention at Computex, and Asustek projects that sales of the low-cost Eee will double to 100 million next year, largely because of the strong demand in target markets in Europe, Asia-Pacific and India. Not only that, but the company has its eye on growing its market share in the U.S., based on market weakness and the consumer spending slowdown.