SAN JOSE, Dec. 16 -- The number of PCs in use worldwide will reach almost 1.3 billion by the end of the decade, up from about 575 million today. In a new study, Forrester Research claims markets in Europe, the U.S. and Asia have reached maturity and that the bulk of the growth will come from emerging regions like China, Russia and India.

According to Forrester, emerging markets will account for 566 million new PCs in use by the end of 2010. The mature regions' consumption: 150 million new PCs in use. (Contrary to other news reports, the study reflects new PCs in use, not sales of PCs overall -- which would be a much higher number.)

Moreover, Western PC vendors won't dominate in those markets in the long term, Forrester says. The firm forecasts PC makers like Lenovo Group in China, which just announced the purchase of IBM's PC division, and Aquarius in Russia will gain share because they are better positioned to tailor the PC form factor, price points and applications to their local markets.

For its report Forrester studied 16 emerging markets representing 62% of the world's population.

China will gain the most new PC users, 178 million, while India will gain 80 million and Indonesia 40 million, the study says. According to Forrester, India's PC adoption -- currently one of the lowest rates in the world -- will grow 37% annually through 2010. Indonesia's growth rate will be 40% per year.

Of the 16 emerging markets, Mexico will have the deepest PC penetration as a percentage of population: 46 PCs per every 100 people.