This is quite a change - if you bought a laptop just a few years ago, it might have cost twice as much as a contemporary desktop PC, but the features it contained could have been nearly a year behind. Now, high- powered laptops are as little as three months behind, while less powerful models sell at desktop PC prices.
The most recent development has been the arrival of new mobile processors from Intel, code-named Tillamook, that provide the same power as the fastest 233MHz desktop Pentium chips. The hard disks used in laptops can match those on the desktop too, with IBM recently announcing a 5GB example, though their higher level of miniaturisation means that they're still around twice the cost per megabyte.
In fact, just about the only features you can't get in portable form are fixed-size ones, like 17 inch screens, as most laptop PCs are designed to occupy the same desk space as an A4 sheet of paper. But they can still pack a lot into that, and some of the latest models use 14 inch liquid crystal displays (LCDs) that offer more usable screen space than a 15 inch desktop monitor.
Keeping up the desktops, is expensive - it requires leading edge technology. The manufacturers know this and usually offer less powerful laptops at more reasonable prices, and for many users these will be the ideal choice. They might have a smaller 11 inch screen and 2GB hard drive, but will be fine for most uses, and their portability is a huge bonus.
Once in the office, there is nothing to stop a laptop being plugged in to all the usual facilities: a local area network, printers, even an external full-size keyboard and screen. Then when you want to work at home or on a business trip, you just unplug and go. Many users keep a duplicate external screen and keyboard at home for when they are working there.
An easy way of plugging in all these things is a docking station, this has a slot into which the laptop slides and it automatically makes all the connections in one go. These are neat, but be warned that different laptops need different docking stations; when you replace one, you'll have to renew the other too.
This ability to plug in extra bits and pieces is one of the laptop's big advantages over the desktop. Instead of needing circuit boards that must be fitted inside the PC, laptops have what is called PCMCIA slots, whose small cards can be inserted and removed without needing to switch the machine off. Thus it's a simple matter, say, to pull out a network card and push in a modem instead.
Some of the latest additions to the mobile user's armoury are various ways of hooking up a PC without needing wires. Local area networks can use radio cards instead of cabling, for instance. This is finding favour in places like warehouses and on campus sites, allowing users to roam freely with their laptops.
Out on the road, an increasing number of users are turning to GSM, the digital cellphone standard used in the UK by Cellnet, Vodafone, Orange and One2one. Standards for GSM include the ability to transmit data and voice, and although it is at least four or five times slower than the latest modems, it can be used almost anywhere.
This is great for international travellers too, because the GSM networks in different countries (excluding most of the USA) are interconnected so that handsets can make and receive calls in any of them. A single GSM card for the PCMCIA slot therefore replaces the need to carry telephone plug adapters.
As the use of laptops grows, airlines too are acknowledging that their passengers want to work on the move. Several are installing laptop power supplies for business class travellers, and some are putting in modem sockets that link to existing satellite sky-phone systems.
Laptops are getting lighter. Hewlett Packard's Omnibook set the standard, weighing less than 4lb (1.7kg), but was recently eclipsed by Toshiba's 2lb (840g) Libretto. It has a six-inch monitor, a hard disk and a Pentium processor.