3. Handwriting recognition software is not up to speed.

"If you write with a page of chicken scrawl, it ain't going to work," Fiering noted.

The software that can be used to turn handwriting into text is not fully accurate, meaning that if your handwriting is sloppy, the text recognition will be poor, Kay added.

Microsoft's Vista operating system is supposed to help with autocompletion of handwritten words but will not help with poor handwriting, meaning that handwriting recognition will not be a key driver of the tablet PC technology, Fiering said. Doctors and salespeople who take notes with tablet PCs are basically interested in saving their handwritten notes for their own use later on, not converting them to text, she explained.

But even saving handwritten notes can be a problem, Dulaney said. He recounted a time when he tried to impress colleagues at a meeting by taking handwritten notes on a tablet and then sending them around quickly to everybody afterward. "What they said back was, 'Thanks Ken, but I can't read your handwriting. Next time, type your notes.' "

By contrast, Brown said character recognition in the ThinkPad X41 Tablets has been "very good," when police officers have to write short descriptions on a form, perhaps one or two paragraphs.

"You have to train the software to recognize the handwriting," he noted. Primarily, having a tablet PC that takes handwriting input in the cramped police cruiser dashboard area means not having to provide added space for a keyboard. (The X41 is a convertible, which means the touch screen can be pivoted and placed on top of the keyboard, saving space over a fully opened laptop.)

4. Until Vista, tablet PC hardware needed a special operating system called Windows XP Tablet PC Edition.

Until Vista, users needed Windows XP Tablet PC Edition to use such functions as handwriting recognition and touch screen. This has meant that a user would face the annoyance of not being able to write in a password to start working, Fiering said. The user would have to type or tap in letters and symbols of the password first before getting to the handwriting capabilities. With the new Vista Business Edition, the tablet capability is integrated, and if the PC is enabled to take touch or pen input, the OS will recognize it, she said.

Vista will also improve navigation for tablet PCs, allowing flicks of the pen to scroll, go back, delete and undo, Fiering said. For example, a user can paste an item into a document or delete text with the flick of a pen. Because of these improvements with Vista, Fiering said, tablet PCs will improve somewhat in popularity.

5. Tablet PC form factors have improved, but still not enough.

Tablet PC screen sizes can only be so big or the machines will weigh too much for users to want to carry them, Dulaney noted. But having a larger screen is something many users want for greater space to take notes.

To keep the weight down, most tablets have 12-in. screens, and many models don't come with an optical drive as a result. None of the 12-in. models has a wide screen, Fiering said. Several manufacturers have introduced 14-in. screen tablet PCs, but they tend to be "heavy and unwieldy," and would limit a user's ability to carry the device to take notes as with a clipboard, Fiering said.

In earlier generations, mechanical problems were also evident, including problems with hinges on convertibles, Fiering said. Providing a latch that will work on the convertible models "still has defied all the hardware design engineers," she noted.

Many new second- and third-generation models are emerging, and Dell is planning a convertible model in midyear, Shim said. Dell would not comment, but Shim said Dell's entry could dramatically improve sales of tablet PCs, if only because Dell has a reputation for its ability to flood the market with less expensive devices.

Dell's entry will also come about the time that miniature tablet PCs hit the market, including the 1-lb. OQO with a 5-in. touch screen. But both Shim and Fiering said ultramobile PCs, including tablet PC variants, will stay in their infancy for the next two years, partly because of high cost and relatively short battery life.

Hewlett-Packard, Lenovo Group, Gateway, Toshiba and several other vendors offer tablet PCs, but "none are clear leaders and all are kind of running in last place," Shim said.