If you spot any errors in this paragraph, don't be dismayed. It was written with new voice-activated software that is billed as a way to operate computer while rarely laying hands on it.

OK, the software did very well: The punctuation is right and nothing is misspelled. But I believe I said it is a way to operate "a" computer.

That trade-off — mostly good, a little bit bad — generally sums up this new software, Dragon NaturallySpeaking 9.

Dragon and other programs that let people control PCs by voice instead of keyboard and mouse have been available for years. They prove particularly helpful for dictation-intensive users such as doctors and lawyers, as well as for people with broken arms, carpal tunnel syndrome and other disabilities.

But Dragon's creator, Nuance Communications Inc. (NUAN), contends that the latest version of the program, released this week, is the first with such a high level of accuracy that anyone would become happier and more productive by using it, since speaking is so much easier than typing.

I put that claim to the test by sampling two versions of NaturallySpeaking 9: the $199 "preferred" setup and the $899 "professional" package.

Nuance also sells a $99 "starter" edition, but the pricier programs are more customizable and work with more Windows applications; for example, you need the pro version to fully voice-activate PowerPoint and Outlook 2003. All come with a headset microphone needed to make the program hear what you say.

In many ways, Dragon is brilliantly constructed. It is intelligent about using context to determine word choice and punctuation.

I didn't have to say "voice hyphen activated" for the opening paragraph; it just knew a hyphen was required. Complain that "Two plus two is too much to add," and Dragon nails all three spellings of the "too" sound.

Also, because higher-end versions of the software let you boil down multistep functions into a single voice-activated shortcut — for example, while using Microsoft Word, you can say, "insert a three-by-five table" and voilà, one appears — there are times when Dragon makes life easier than using a keyboard and mouse alone.

And it certainly feels great to kick back while reading and writing e-mail, uttering the occasional "next message" or "delete" or "reply" or "send" as if dictating to an invisible servant. If you ever forget what Dragon can do in a given Windows application, simply speak "What can I say?" and a list of commands pops up.

Still, I wouldn't go so far as to say I was more productive with Dragon. Even with all of Dragon's admirably well-designed features, it's a stretch to call it a must-have for anyone outside the usual market of people with disabilities, sore wrists or voluminous typing responsibilities.

For one thing, even though we speak much faster than we type, especially when typos are factored in, unless you enunciate with an inhuman level of precision, Dragon will make its share of mistakes.

Dragon has a cool way to fix its errors: You tell it to "select" the erroneous text and it pulls up a menu of likely changes. Then you simply speak the number corresponding to the right correction.

But the right choice isn't always in the menu. In that case, you have to spell it out for Dragon or type the correction. Sometimes using the keyboard and mouse from the start turns out to be faster and easier.

Another hitch comes with Web surfing. Dragon mostly is adept at this.

Notably, if you speak the first words that correspond to any link on a page, the software will quickly order the Web browser to take you there. But with other functions, like scrolling a page or entering text in forms, there's just enough of a lag time between the utterance and the action that the usual method of grabbing and clicking the mouse feels more fluid.

Indeed, Dragon's own tutorial notes that in Internet Explorer, "even though you can do everything by voice, many people find it more efficient to use a combination of mouse, keyboard and dictation."

Perhaps most annoyingly, while Dragon might be great at interpreting what it hears you say, it won't always hear you. If the microphone shifts into an odd position, or you mumble, Dragon can be at a loss for words.

The initial setup of Dragon — which requires Windows XP, 1 gigabyte of hard-drive space and 512 megabytes of RAM — is easy. Version 9 is the first that lets you skip the tiresome process of "training" the software for your voice; now the program can figure it out on the fly. It also can study your e-mails and documents to learn your personal writing style and thus better guess what you mean when you say certain things.

But a few times Dragon froze and crashed. It's a relatively common issue that stems from a conflict with a Windows file that runs in the background to help the PC recognize alternative methods of text input. If you disable this particular process, Dragon can run unencumbered. It's not a difficult step, but it might unnerve some users to tinker with their PC's operations.

Ultimately, I'd bet that many people would find Dragon a useful companion to the usual methods of interacting with a PC. It's certainly nice to type less.

But it's hard to see voice becoming the primary method for input. There remain few things in life that solve a problem without creating new problems of their own.