Three years is a very long time in mobile computing. If you bought a handheld PC back in 1999, chances are it would have been manufactured by either Palm or Psion.
In 2002, Psion no longer makes PDAs, and Palm has seen its market share tumble as devices that use Microsoft's Pocket PC operating system have come to the fore.
Today, connected PDAs featuring integrated mobile phones to enable the user to make voice calls, collect and send emails and surf the net, are edging ahead of traditional unconnected handheld in terms of sales.
Arguably most representative of the way the PDA market is likely to develop is the £500 Pocket PC based XDA, launched recently by the MM02 network. It is smaller and lighter than many of its rivals, boasts an excellent colour screen and seamlessly integrates Pocket PC applications into the mobile domain.
Its key advantage is its GPRS (General Packet Radio Service) connection, a rarity in the smartphone world, which means that downloading emails and accessing web pages is faster and cheaper than it would be with standard GSM.
The XDA may soon be available under another guise through T-Mobile. The network has unveiled the Pocket PC Phone Edition, a product that's a dead ringer for the XDA, in the United States and is promising a UK launch soon.
Samsung has announced that its large connected handheld PC, the Nexio 160, will arrive in the UK at some point in the autumn. The product has a strong line up of features, easy connectability to the PC and web surfing and email facilities. Its trump card is a 5in LCD screen - much larger than any of its competitors. Internet pages are easier to view than on rival mobiles, while applications such as Word and Excel (the device uses Microsoft's Windows CE system) are less fiddly to operate.
Other features include a USB port enabling owners to connect a mouse, keyboard or memory card and integrated software for games and music. No news yet on price.
The Pocket PC/Windows CE camp doesn't have it all its own way. Handspring, whose PDAs use the Palm operating system, has just unveiled the Treo 270, the second version of its connected PDA, which adds a colour screen to its predecessor's facilities.
There's no GPRS version yet, although Handspring says it intends to offer a free upgrade for the Treo shortly. In its favour, the Treo's thumb pad (a kind of mini keyboard) is simple to use and the device is more pocketable than most of its rivals. It sells for around £550 without a SIM card - cheaper as part of a deal.
Already available in the United States, and possibly coming to the UK, is the Kyocera Palm-OS based smartphone 7135 colour screen PDA.
It's a flip phone with a smaller screen than the Treo. Features include an integrated MP3 player and a slot for Secure Digital (SD) cards to add memory or functionality.
The market for unconnected handhelds may be contracting, but there are still plenty of impressive new products being launched.
Compaq HP (after its recent merger with Hewlett-Packard) is touting its H3900 series models - the successor to the enormously successful Compaq iPaq H3800 series PDAs. Two models are available; the £600 H3950 and £700 H3970. The main difference is that the H3970 features Bluetooth for wireless connection to a mobile, and has 64MB of Flash ROM as opposed to the H3950's 32MB.
Cosmetically, there's little difference between the new PDAs and their predecessors. Slip under the hood, though, and you'll find a faster processor (the latest 400MHz Intel PXA250 as opposed to the 206MHz Intel StrongArm of the 3800). Compaq HP claims that this will give it the edge in terms of speed of applications, but also for entertainment facilities such as watching video clips using Windows Media Player. Another neat touch is a feature called Nevo that enables you to programme the PDA to control all your home entertainment devices.
If the rather chunky iPaq is too weighty for your pocket and your wallet, Packard Bell recently launched the £379 PocketGear 2060. Smaller and lighter than rival Pocket PC-based devices, it has a good quality colour screen, is expandable via its Secure Digital card slot and features a 206MHz Intel StrongArm processor, as found in older Compaq iPaqs.
In the Palm operating system camp, Sony is continuing its policy of refreshing its line up of Clié PDAs every few months.
The Clié PEG-T665C features what Sony is billing as an improved colour screen, boasts a 66MHz processor - currently the fastest chip available for Palm - and, like PocketPCs, comes with music and video-playing software. It is due in the UK later in the year for around £400. Just like Compaq HP iPaq H3900 series PDAs it, too, can moonlight as a remote control for your TV. Just don't lose it down the back of the sofa.
