The first laptops powered by Google Inc's Chrome system will hit store shelves later than expected, as the Internet company works out bugs in a family of Web-centric computers intended to take on Microsoft Corp and Apple Inc.

When launched, the computers will represent Google's strongest foray into consumer and business computing, where most PCs are now powered by Microsoft or Apple systems.

The new Chrome-based notebooks, to be sold initially by Samsung Electronics and Acer, will come with just 100 megabytes of free wireless data transfers per month for two years, courtesy of Verizon Wireless.

According to Verizon Wireless, streaming video for 2 minutes every day amounts to 260 megabytes of data downloads over a month.

They are designed to promote Web-centric computing, in which consumers employ online applications instead of working off software on PCs.

To drive that, the company started up on Tuesday an Internet store selling some 500 games, news and other software applications for Chrome, carving out a bigger role in the next generation of Internet media and entertainment.

Executives said Google would leave retail prices to manufacturers to set. The company did not say how the Chrome operating system would contribute to its profit.

On its official blog, Google said it had decided to hold back launching the widely anticipated series of Chrome-based PCs until any bugs had been worked out.

Amazing progress, but we aren't fully done yet, Chrome product manager Sundar Pichai told reporters at the launch event in downtown San Francisco.

BLACK IS BACK

More PC manufacturers will come on board eventually, executives said without identifying any.

Google has begun a pilot program under which it will distribute prototype Chrome-based laptops to schools, select businesses, developers and other qualified users with the intent of collecting feedback.

The all-black CR 48 prototypes come with 12.1 inch screens, 3G connectivity and webcams but do not have any logos or branding whatsoever.

We're not done yet, but Chrome OS is at the stage where we need feedback from real users. Some of the features of Chrome OS require new hardware, but we didn't want to sell pre-beta computers, the company said on its official blog.

Apple, maker of iPhone and iPad and one of Google's competitors, said in October that it would open an applications store for its own Macintosh computers, as it tries to replicate the success of apps sold for its iPhone. That store is expected to go live early next year.

Electronic Arts demonstrated a game that is due to go on sale on the Chrome software store later on Tuesday. The online store will also sell applications to run news.

Google executives also told a news conference in San Francisco that the Chrome Internet browser, on which the similarly named operating system is based, has 120 million users. In May, it had 70 million.

Shares in Google were up 1.4 percent at $586.68 in late afternoon trading on the Nasdaq.

(Reporting by Alexei Oreskovic and Edwin Chan, editing by Robert MacMillan, Bernard Orr)