It's high time people looked at how they carry mission-critical personal information.

The chances are you have files on your home or office computer containing your most important addresses, phone numbers, diary events, notes and lists of things that have to be done.

You may use Microsoft Outlook or Lotus Organiser to keep your life in order.

But unless you carry a notebook computer with you at all times, you simply can't access vital data when you are out on the town.

The answer is a personal digital assistant or PDA.

It's a single information storage device that sits comfortably in your pocket but can link with your PC to synchronise diaries, address books and personal data.

The choice is huge, ranging from a £10 pocket organiser with the street cred of a Skoda to the slickest brushed aluminium-style statement that draws attention from the people who matter.

Top buy is still the undeniably suave 3COM Palm Vx. Currently the world's top-selling PDA, the Palm is light enough to drop into a shirt pocket and powerful enough to handle your entire life.

It sports an extremely sexy metal case with high-grade leather cover and ships complete with an elegant docking cradle that doubles as a battery recharger.

Other features include:

On-board infra-red technology allows data transferral to other Palm Vx users via an invisible IR beam.

HotSync button that instantly backs up and exchanges data with a PC. Desktop organiser software is included in the price.

Touch-screen technology and character recognition software allows data input via an easy-to-use ink-free stylus.

Memo Pad allows the user to make notes, jot down directions, enter the name of a restaurant and then save the data digitally.

Address Book lets the user store thousands of addresses, phone and fax numbers and even has space for e-mail addresses.

Date book makes it easy to remember meetings and appointments. It even has a built-in alarm to ensure vital dates are not forgotten.

The Psion Series 7 is a real powerhouse that feels like a brick in your pocket.

But it offers plenty of features, including a larger-than-average keyboard, a huge full-colour screen and e-mail/mobile phone connectivity.

A clever zoom control allows users to magnify part of the screen.

But it's massively overpriced and the best feature of the Psion Series 7 is it's British.

The Sharp ZQ-485 is a value-for-money PDA with a great pedigree.

Features include keyboard data entry, metric and currency conversion function and a PC-link kit included in the price.

With a three-file telephone directory, a scheduler with alarm and anniversary reminder and a home and world clock, the ZQ-485 offers plenty of PDA for very little wonga.

The HP Journada 545 is something of a new kid in the PDA marketplace.

It offers the latest Microsoft Pocket PC operating system complete with integral MP3 player, colour screen and Windows Media Player that allows you to read electronic books.

It has an interesting design and feels tough and workmanlike.

Operation is easy but a touch uninspiring. However, loading large volumes of text via the touch-sensitive screen is relatively quick and easy.

The Casio Cassiopeia also runs on Microsoft's new operating system and supports pocket versions of your favourite MS Office applications.

It looks very classy and has attracted a lot of comment but generally fails to live up to expectations.

Operation is slightly awkward, the buttons are unpleasant to use and the unit is horribly expensive.

Sharp ZQ-485: £55 Contact: 0800 262 958 Psion Series 7: £655.65 Contact: 0990 143050 Palm Vx: £299.99 Contact: 0800 7311 064 HP Journada: 545 £369 Contact: 0990 474747 Casio Cassiopeia: £499.99

Contact: 0208 450 9131