XP Specifications

300 MHz processor 128 MB Ram 1.5GB hard disk space Super VGA video adapter CD-Rom or DVD drive

But even consumers may balk at paying for XP because it offers them little that they do not do already.

The lack of queues outside the stores that opened up at midnight to sell Windows XP shows how few people are planning to upgrade their existing machines with the software.

There are good reasons not to. For a start, Windows XP, even more than earlier versions of the operating system, is a resource hog.

Microsoft recommends that anyone running XP have a computer with a 300 MHz chip inside, a 128 megabytes of RAM and over 1.5 gigabytes of hard disk space.

Market research firm Metafacts estimates that the majority of machines in the US (58%) have 64 megabytes of memory. Those with enough RAM account for only 21% of all desktops.

Old software

Those without enough memory are unlikely to buy more simply to get the new operating system.

Massive marketing push behind XP

This is because their machines are likely to be older and the problems of moving ageing programs, favourite games and tweaked settings to an upgraded machine could be formidable.

To help those brave enough to upgrade, Windows XP arrives with a helper program that will try to work out whether your machine is powerful enough to run the software.

This software is intended to pick up any potential problems with software incompatibilities, but early reports suggest that there are some things this helper misses.

Microsoft is also providing an "Upgrade advisor" program that can check your machine before you install. Though the program is so large that few people are likely to download it.

Another helper within XP will migrate your files and settings to an upgraded machine, but again it is not yet clear whether the format that these older files were created with will be preserved, ignored or altered by XP.

Recent games

In the past, many organisations have had problems swapping files between machines running different generations of Windows.

Pre-release versions of Windows XP have been lacking programs that help Windows work with peripherals. Microsoft's XP website should hold the latest information about installation problems.

Games released in the last year or so that work with Windows 98 and/or NT should work with XP. Although, Microsoft has yet to provide any guidance on this.

Many games bypass Windows and work by talking directly to the hardware in your machine. Changing the operating system should not affect their ability to run.

However, so far, Microsoft has not provided much information about which older programs will work with Windows XP. As yet it is unclear whether files and documents created using older versions of software packages will work with the new version of Windows.

Network alternative

Given this uncertainty few people are likely to upgrade and many more will encounter Windows XP only when they buy a new PC.

It might also be easier to set up a network at home connecting your old machine and its files to a new PC running XP.

A network hub and adapter cards for a couple of PCs can be bought for less than �100.

Versions of Windows 98 and above do a good job of hiding the complexity of setting up a network, often machines will find each and recognise each other as soon as they are connected.