Microsoft unveiled a revamped version of its flagship Windows system Thursday designed for increasingly mobile consumers and previewed Surface, its entry into the hot tablet market. The new Windows 8 operating system and the new tablet to go on sale Friday mark a new offensive for the US tech giant seeking a new strategy to keep pace with Apple and Google and a dramatic shift away from PCs to mobile devices. \"Windows 8 brings together the best of the PC and the tablet,\" said Microsoft chief Steve Ballmer. \"What you have seen and heard should leave no doubt that Windows 8 shatters the perception of what a PC really is... It works perfect for work and play and it is alive with your world.\" At a New York news event, Microsoft announced that Windows 8 will launch Friday in 37 languages and 140 worldwide markets. It can be downloaded beginning at 12:01 am local time worldwide and will be sold at retail stores. Microsoft is also launching a version called Windows RT, designed for tablets and available pre-installed on new devices including its own Surface tablet. Some analysts point out the Windows RT offers Microsoft a chance for a fresh start in controlling both hardware and software in a single device. The new tablet system \"represents the best shot Microsoft has against Apple and Google,\" said Roger Kay at Endpoint Technologies Associates. \"WinRT is where things are going.\" The software giant gambled by changing long familiar user interface features to make Windows 8 compatible with trends toward keeping programs and data in the Internet \"cloud\" and relying on mobile gadgets at work and at home. Surface, which seeks to challenge Apple\'s market-ruling iPads and rivals built on Google\'s Android software, will be among Windows-powered devices sold in real-world Microsoft stores that will \"pop up\" on Friday in the United States and Canada. Microsoft promised that the temporary, holiday-season shops will feature a \"curated collection of Microsoft\'s coolest products.\" The news comes two days after Apple introduced its \"iPad mini\" in a bid to crowd out lower-priced offerings by rivals Amazon, Google and Samsung. Surface -- a late entry in the market -- has a 10.6-inch (26.9 centimeter) screen and starts at $499, challenging the larger-format iPads. But Surface appears to be a cross between a tablet and a PC, equipped with a flip-out rear \"kickstand\" to prop it up like a picture frame and a cover that, when opened, acts as a keypad so tablets could be switched into \"desktop\" mode for work tasks. It launches in a crowded market for tablets from Apple, Google, Amazon and others, amid forecasts that global tablet sales will surpass those of PCs within a few years. Windows 8 and an accompanying version of Microsoft\'s free Internet Explorer web browsing program were designed to optimize touch-screen capabilities in tablets and various \"convertible\" PCs. Windows, the first version of which was launched in the 1990s, remains the dominant PC platform with some 90 percent of the world market. But in the mobile world, it is struggling against Apple\'s iOS and Google\'s Android system. Microsoft reported that pre-sales of Windows 8 have outstripped those of its predecessor by 40 percent. The Redmond, Washington, company next week will provide details on its new Windows Phone 8 operating system designed for its push into the smartphone market.