Microsoft has joined forces with the developers of the "$100 laptop" to make Windows available on the machines .The move was prompted by countries which demanded the operating system before placing an order. Trials of laptops loaded with Windows will begin in "four to five" countries from June, the organisations said. The founder of One Laptop Per Child (OLPC), which developed the machines, denied the move was a "desperate new measure" to secure more orders. Who wants to bet that government education departments, already far more familiar with Microsoft's operating system, will now opt for the Linux alternative?

"While it is certainly true that it has not taken off as fast as I would have hoped and publicly stated, certain countries around the world, have always been very, very insistent that they want Windows as an option," Nicholas Negroponte told. Until now, the XO machines, as they are known, have only been offered with an open-source Linux operating system. OLPC originally aimed to sell the low-cost laptops in lots of one million to governments in developing countries for $100 each. The innovative machines, which have been designed for use in remote and harsh environments, were to be distributed to school children. Over time, however, the project was forced to drop the minimum number of machines that could be ordered. Each machine currently costs $188 ($198 with Windows XP). So far, it has sold just 600,000, according to Professor Negroponte, although he said it expected a further 400,000 orders in the next "60 to 90 days". "There is no question that demand goes up when you offer dual boot," said Professor Negroponte.

Machines will eventually be offered with the ability to run either Windows XP or Linux, although he admitted there were still some technical issues to overcome to achieve this. "I liken running Windows in dual boot on the laptop as exactly what Apple did on their machines," said Professor Negroponte. "A lot of people moved to the Apple laptop once it had that dual boot."

It has taken Microsoft nearly one year to make its software compatible with the XO machine. It will cost an additional $3, plus $7 for hardware, and will be offered on a 2GB memory card that can be plugged into the machine. The laptop has been designed for use in developing countries. According to the Microsoft, it supports many of the XO's unique features including its custom keys, writing pad and power-saving mode. Crucially, however, it does not currently support the mesh networking that allows the computers to talk to one another and share data.

In addition, the user interface designed for the XO - called Sugar - does not yet run on XP, although Professor Negroponte said that OLPC would work with "third parties" to find a solution to this. The options afforded by Windows will be welcomed by the governments of countries, such as Egypt, which has insisted on being offered the operating system before signing up to the scheme. Other customers and partners have already applauded the shift. "Windows support on the XO device means that our students and educators will now have access to more than computer-assisted learning experiences," said Andres Gonzalez Diaz, governor of Cundinamarca, Colombia. "They will also develop marketable technology skills, which can lead to jobs and opportunities for our youth of today and the work force of tomorrow." However, others have been less forthcoming with praise about the opportunities Windows affords. "[OLPC] should not believe the nonsense about Windows being a requirement for business after the children grow up," wrote Ivan Krstic, who recently resigned as the organisation's top security architect, on his blog.

"Windows is a requirement because enough people grew up with it, not the other way around. If OLPC made a billion people grow up with Linux, Linux would be just dandy for business." Mr Krstic said that he was enthusiastic about Sugar being made available on the "most widely used operating system in existence" but was opposed to Windows becoming "the single OS that OLPC offers for the XO". "[OLPC] should not become a vehicle for creating economic incentives for a particular vendor," he wrote.

Whilst Professor Negroponte said this was not the intention, he could not rule out the possibility of XP becoming the sole offering in the future. "If that's the way it unfolds, that's the way it unfolds. We are in the learning business and what the operating system is underneath is less germane," he told. "A lot of it will end up as what governments and educational institutions choose to use," added James Utzchneider of Microsoft.