As the rise of Apple Inc.'s iPad and other tablets threatens its low-cost laptop business

The world's second-biggest PC maker by shipments said Tuesday it will release in February a tablet running Microsoft Corp.'s Windows software with a 10.1 inch screen.

Acer will also release two tablets using Google Inc.'s Android software in April, one with a 7-inch screen and one with a 10.1-inch screen.

In addition, executives at the Taiwan company unveiled a portable computer with two touchscreens dubbed the Iconia Touchbook. The laptop opens to reveal a second touchscreen in place of a keyboard. The product will be launched in the U.S. and some European countries in December and will retail for $1,499.

Acer, which had unveiled plans for tablet-style machines in May, is the latest company to jump into the increasingly crowded tablet market after Apple's iPad, released in April, attracted strong consumer demand. Samsung Electronics Co., BlackBerry maker Research In Motion Ltd. and Hewlett-Packard Co., have also announced plans to introduce tablets.

Jim Wong, an Acer senior corporate vice president, said he expects 40 million to 50 million world-wide tablet unit sales next year, with hopes Acer will gain 10% market share.

For two years, Acer has relied on netbooks -- tiny, low-priced laptops -- to propel growth. The company's products, especially its Aspire One, proved so popular, Acer vaulted over Dell Inc. to become the No. 2 PC maker behind Hewlett-Packard.

But worries have emerged that the popularity of the iPad and other tablets could eat into netbook sales. After tripling to $14.3 billion in 2009, netbook sales are expected to slip nearly 2% this year, according to research firm IDC. In 2011, the market is expected to shrink further.

Acer didn't provide details about pricing for its tablets during its product event in New York. But in an interview after the event Jenda Chen, director of product management at Acer America, said the 7-inch Android tablet will likely sell for $399 to $499, while the larger Android model will most likely be priced between $399 and $649.