Dell Inc. has been playing around with mobile devices for more than three years now, but now it finally looks to be making a serious entry into that market.

The Round Rock, Texas-based unveiled its latest generation of computers in New York on Wednesday. The features two Windows-based tablets with 11-inch and 8-inch screens and two Android-based tablets with 7-inch and 8-inch screens.

The launch marks the latest new beginning for Dell Inc. in tablets, and the company is taking pains to emphasize that it is making a serious concerted effort and a long-term commitment to the market.

The outcome is significant to the company's future. Dell, which has nearly completed its management buyout, is in the process of transforming itself into a far more sophisticated and complete supplier of information technology.

But an important part of that transformation plan, as the company has explained, involves staying strong in the personal computer business and somehow finding a way to succeed in tablets after at least one false start.

So why the big tablet push? Because tablets are growing fast in global sales, and personal computers aren't. And because tablets are increasingly being used in businesses either as a companion product or a replacement for traditional PCs.

International Data Corp., which tracks technology markets, estimates that worldwide tablet shipments will outpace PCs in the fourth quarter of this year. It also projects that tablets will surpass PCs in annualized shipments for the first time in 2015.

While PCs remain far more powerful devices, industry experts and Dell officials acknowledge that tablets are gaining ground in the businesses workplace. And selling information technology to business remains Dell's primary thrust.

"It is clear that tablets are where the action is and where the growth and excitement is," said analyst Roger Kay with Endpoint Technologies Associates. "It is an area that Dell has to be in. This product launch is them investing in the future."

The challenge for Dell is that it is almost invisible in the tablet market, which is presently dominated by two companies, Apple Inc. and Samsung Electronics Co.

Dell also has the early missteps in the market to overcome.

The company exited the Android in 2011 after never making much of a dent.

Then late last year Dell quietly introduced two new Windows tablets based on Microsoft Corp.'s touch-enabled Windows 8 and Windows RT software systems. Dell is discontinuing its Windows RT model, which was based on a version of Windows written for non-Intel processors.

Instead, Dell's new tablets will be all Intel-based, although two of them will use Google Inc.'s Android software.

With the new generation, Dell is emphasizing their look and feel, along with a longish product life.

"If you buy (a Dell tablet) in holiday 2013, you should still be happy with it in holiday 2014 and 2015," said Neil Hand, a Dell veteran who had left the company several years ago, but returned last year to become vice president for tablets and performance PCs.

Hand can make that claim because of dramatic progress by Intel Corp. in making processors that successfully combine low power use and stronger performance.

Most of the new Dell tablets are based on Intel's new Bay Trail version of its Atom family of processors. The Bay Trail chips are expected to deliver at least three times the performance of previous Atom mobile chips.

Along with its new tablets, Dell also will have a docking station, called a Desktop Dock, that lets the tablet be plugged into a much larger display. It also is offering two versions of keyboards, one with full-motion typing keys and the other, a thinner keyboard, with typing keys that have less movement.

The idea is to give customers a solid work-related system that also can function as a personal entertainment system for things like reading books and watching movies.

Dell is offering its Pocket Cloud service to enable its tablets to share documents and data with a wide range of other devices. It acquired the Pocket Cloud technology when it bought California-based Wyse Technology last year.

Like almost all tablets, these machines are made in Asia, but Hand said considerable engineering effort from Dell engineers in Austin, Texas, and California's Silicon Valley went into the designs of the new models.

The new tablets are expected to be available online and with retailers in the next few weeks.