The theory behind the IO Personal Digital Pen is sound. You want to write onto paper, but want your notes and drawings stored on your PC too. So, you use a pen that digitises and software that can turn your doodles into images, your handwriting into text. That's pretty much what Logitech has achieved here, and it is simply amazing that the whole thing works.

You need to write onto what Logitech calls 'digital paper'; that is, paper whose background is covered with tiny dots, so that the gubbins inside the pen can turn your writing into computer-readable information. Because the pen has a standard ink cartridge, you can also use it on ordinary paper, though you won't get the benefits of digitised data if you do. When you're back at your PC, you drop the pen into a docking cradle and its data goes to your PC.

Here's where the really clever stuff happens. Depending on how you've marked up what you wrote, which in turn depends on what you've written in various designated areas on the digital paper, your notes might wing their way off to your e-mail software, your diary, or your 'to do' list.

Or they might sit in the Logitech desktop software where you can edit them and then either keep them or save them as Microsoft Word documents with embedded graphics, or image files in various common formats. Alternatively you can export them to a piece of third-party software where your handwriting is turned into editable text.

If you like the idea of using the handwriting-to-text option, note that Logitech only supplies a trial version of the MyScript Notes software that does this job. After the 30-day trial is up you'll have to pay £30 to carry on using this software.

In our tests the IO Personal Digital Pen worked pretty well. It is a bit large to hold in the hand, but what we wrote digitised nicely, and as long as we wrote clearly and carefully the handwriting-to-text feature functioned pretty well too.

With 1MB of memory (enough for around 40 A4 pages of text) and battery power for around 25 pages of writing, you are going to need to get to your PC to download data and recharge the pen regularly, and you also have to consider the ongoing costs of buying digital paper, which Logitech sells from its www.logitechio.com Web site. Add these to the cost of the pen itself and you can expect a fair outlay.

The IO Personal Digital Pen is a fascinating idea and anyone who spends a part of their life beyond the range of their PC may feel drawn to it. Before rushing out to buy, though, remember the battery and internal storage constraints and the fact that you'll need a supply of digital paper.