The One Laptop Per Child Program, in efforts to spread sub-$200 computers to schoolchildren in developing countries, has reached a milestone with the start of mass production.

The nonprofit spinoff from MIT said assembly lines for its “XO” laptops were fired up on Tuesday at a Quanta Computer factory in China. Meaning children (and donors) should begin getting the green-and-white linux laptops this month.

One Laptop Per Child did not say how many computers will be made or how many orders it has received from buyers. The program’s founder, Nicholas Negroponte, said in September that Quanta would build about 250,000 XOs this year, ramping to 1 million a month in 2008.

The computers were dreamed up as $100 laptops but for now cost $188, this will no doubt fall as production goes into overdrive.

The initial recipients will be children in Uruguay, Peru and Mongolia. Also, beginning Monday, people in North America will be able to buy one for themselves and donate the other to a child overseas through http://www.laptopgiving.org .

Even with mass production beginning later than expected, One Laptop Per Child can claim success on several fronts. The small yet rugged XOs require low power and can be recharged by hand, have a screen that can be read in full sunlight and boast a user interface designed specially for children. The impending emergence of the XOs has shown other companies that there is a market for a sub $200 laptop in developing markets.