So you've got a cell phone in one pocket, an MP3 player in the other, a laptop in your briefcase, and maybe a personal digital assistant somewhere in between. Oh, one of your kids has the latest game handheld, too.

Is there room for another gadget in your life? Microsoft Corp. apparently thinks so.

Though all those gadgets are becoming more powerful and multifunctional themselves, Microsoft is stepping into the risky business of introducing yet another portable gizmo.

On Thursday, the software company took the wraps off its mysterious Project Origami and along with its hardware partners unveiled a new breed of PC — an ultramobile, full-fledged computer that weighs about 2½ pounds, is the roughly the size of a paperback book and features a 7-inch touch screen.

With prices expected to initially land between $500 and $1,000 and a battery life that so far spans up to three hours, even Microsoft acknowledges that sales will be limited in the beginning. But the hope is that with technological improvements over time, the ultracompact PC will eventually cross over from early adopters to attract mainstream buyers.

If the category were to survive the portable battlefield, analysts say it will likely take at least another two years before the product gains market traction.

"I don't think it'll flame out, but I don't think it'll take off until 2008," said Samir Bhavnani, analyst at Current Analysis.

Still, its share of the PC market will maybe at best reach 7 percent at that point, Bhavnani predicted.

Consider today's reality within the world of portable computers: small notebook computers that weigh less than four pounds make up less than 1 percent of the total sales of portable PCs sold at retail in the U.S., according to Current Analysis.

That's compared to a 34 percent share of so-called thin-and-light notebooks that weigh 4 to 6 pounds; a 51 percent share of laptops that weigh between 6 to 7 pounds; and 14 percent of bulkier laptops that are typically used as desktop replacements.

More importantly, the mini computer also will have to compete for consumer dollars against the current crop of popular — and less pricey — portables, such as the iPod, the PlayStation Portable and the Palm Treo and BlackBerry smart phones.

Indeed, the Windows-based ultramobile PC is different and technically more powerful in some ways than those handhelds.

It has a 60-gigabyte hard drive. It runs the Tablet PC edition of Windows XP and will later run the new Windows Vista operating system. It has a microprocessor similar to ones found on regular laptops. It supports wireless Bluetooth and Wi-Fi technologies, and sports two USB ports.

Essentially, it has the brains and brawn of a computer — only in one of the smallest packages yet.

At the same time, it is too large and heavy to fit in pockets. It lacks a keyboard. And the battery life is barely enough to last a full-length movie.

Analysts predict manufacturers will come out with add-on keyboards or better yet, smartly integrate one into the design so users can more easily do computing tasks when they want and where they want.

Battery life improvements are also expected, as companies, including Matsushita Electric Industrial Co. Ltd.'s Panasonic, are already introducing advances there.

A docking station that would link the ultraportable to a normal computer setup at home or at the office would also be a smart, helpful addition, analysts say.

And other innovations are sure to emerge.

Already, Pharos Science & Applications Inc., a GPS technology provider, said it will introduce in April a satellite navigational receiver specifically designed to work with this new class of PCs.

Still, how would the compact computer fit into someone's tech-laden world?

Analysts don't expect the gadget to replace cell phones, iPods, the Sony PlayStation Portable, or PDAs, all of which shine in their respective primary functions as either a communication device, digital media player, an entertainment platform, or a personal calendaring and contacts keeper.

But if ultramobile PC makers create the right set of features, then some analysts predict the device could appeal to consumers as a secondary or third computer — one that could store and play a user's digital photos, videos or music, and entire business files, and be small enough to tote around to different parts of the house, or on-the-go.

"At the end of the day, consumers will decide whether the device will make their lives easier," Bhavnani said. "If the answer is yes, then they'll add it to their repertoire."