"Your HP Jornada already includes the full suite of software you need to function as a mobile professional," the first page of the manual for this personal digital assistant says. I wasn't sure about the "mobile professional" bit, but as someone who often finds himself regularly writing "to do" lists just to keep on top of things, the chance to try out a personal digital assistant for a week was likely to prove interesting. The idea of having a PDA appeals to me, but I was not sure if I could justify spending upwards of £200 (€254) for a gadget many believe is just a glorified electronic diary.

Unlike early versions of PDAs, the HP Jornada 540 (price: £469) is sophisticated and powerful enough to be considered a computer on its own. It uses a 133 MHz processor and has 16MB of memory, which can be expanded even further. It is powered by Microsoft's new Pocket PC operating system.

I was pleasantly surprised at the diminutive size of the HP Jornada, which fitted neatly in the palm of my hand and weighed not a great deal more than my mobile phone. It also starts up instantly without any of the delay that you would expect on starting up a desktop PC. The screen is a bit small but graphics quality is excellent, and using the plastic "pen" (called "the stylus") to navigate the touch-screen operating system quickly became second nature. It's possible to navigate using your finger, but this is probably not recommended.

I was unable to connect to the Internet because, even though I have a mobile phone with an infrared wireless connection facility, it turns out that only some of the newer phones on the market can be used as wireless modems. However, cables are available for certain models that can link compatible mobile phones to a PDA for sending emails or surfing the Web.

The Microsoft Pocket PC operating system is reasonably user-friendly, but sometimes a bit perplexing if you're used to using Windows on a desktop PC. Besides the obvious functions that a PDA should have, such as a calculator, calendar, task list and a contacts database, it also features pocket PC versions of Word, Excel, Outlook, Media Player, and even a Reader application, through which you can download books in electronic form. Great for when you're stuck at the airport.

The handwriting recognition technology feature works very well and is actually faster than typing out notes using the stylus and on-screen keyboard. You can also do voice dictation or recording or even download sound files, but the sound quality from the speaker is a bit tinny, even with the volume turned up. Apart from these necessary functions, one of the "killer applications" of today's generation of PDAs is the ability to synchronise with a desktop PC. This has obvious advantages in that you will always have the most current version of your appointments or contact book wherever you are. In addition, you will always have a back-up of the contents of the PDA if it is lost. The task of setting up the synchronisation between my (Windows) PC and the PDA proved to be very easy, and it only takes a few seconds each time synchronisation is carried out.

Is the HP Jornada worth the money? For exceptionally busy, disciplined, technology-savvy people, the answer is yes. As for me, I'd probably be better off with a cheaper and less powerful Palm model. Alternatively, you could set the alarm on the Jornada to wake me up when the price drops to about £250.