Last week Amazon announced it had taken more money for a pre-ordered product — in excess of $20m (£12m) — than ever before. The item wasn’t a video game or a new Harry Potter book, but an operating system, the software you need to run a computer. In just eight hours, Amazon pre-sold more copies of Microsoft’s Windows 7 than it did of its unloved predecessor, Vista, in 17 weeks. The geek aristocracy and early adopters had obviously made up their minds that Windows 7 is a must-have piece of software.

Certainly, for anyone still using XP, the eight-year-old system running on many laptops and corporate PCs, the improvements offered by Windows 7 are considerable. Windows 7 will run faster, demand less processor power and nag its users less frequently than did Vista, which was one of the biggest complaints levelled at the system.

It looks very different from XP, too. Gone is the grey, boxy layout, replaced with a colourful, curvy, Vista-like desktop and icon-based shortcuts to files and programs. For all the improvements, though, Windows 7, which was launched last week, is still essentially an upgrade, or “service pack” as Microsoft calls it, of Vista. The reason Microsoft has chosen not to call it that is because Vista has been a disaster since its release in 2007. Remember when the Windscale nuclear plant was renamed Sellafield to expunge memories of a fire? Windows 7 is the software equivalent.

The problems with Vista began when it was installed onto machines that were not powerful enough to handle its see-through graphics and constant background indexing of files. In addition, it was incompatible with many users’ existing hardware, such as cameras and scanners, and it had the irritating habit of questioning every action you took on the grounds of security.

Many of those glitches could be solved by altering the system’s settings, while third-party manufacturers soon released patches to make their kit compatible, but the damage had already been done: Vista was deemed a flop.

Microsoft is the world’s biggest software company, claiming a billion users of its products worldwide. But many of them have stuck with XP rather than upgrade to Vista. The vital corporate market, in particular, stayed with software it trusted, while the new breed of small, cheap netbook portables were unable even to run the bloated Vista software. Microsoft was forced to backtrack on its pledge to stop supporting XP. To heap on the ignominy, some laptop makers offered vouchers for Vista customers to downgrade their operating systems back to the older version.

How to upgrade to Windows 7

To upgrade to Windows 7 you don’t necessarily need a new PC. A key virtue of the system is that it runs more easily than Vista on an old machine or netbook.

First, download Microsoft’s Upgrade Advisor tool (free at tinyurl.com/qumqcc) to see if your PC is up to the job. This will also alert you to any incompatible drivers or software that you either need to update or uninstall before taking the plunge. You must then choose whether to do a custom install or an in-place upgrade. The former expunges your old applications and settings whereas the latter promises to keep any files, settings and programs from your current Windows system. Note that an in-place upgrade is only possible with specific editions of Windows.

Either way, it’s wise to perform a complete back-up of personal data on your hard drive before following the on-screen instructions. Microsoft offers a fuller guide at tinyurl.com/yd4l5e6.

The good news is that Windows 7 is the software Vista should have been from the start — “undoubtedly the most usable Microsoft operating system to date”, according to PC Pro magazine. It demands far less operating memory, so will run on netbooks; it simplifies the everyday tasks demanded by most users, such as connecting to wi-fi networks and launching programs quickly; and it incorporates smart new ways to save files without cluttering the desktop, but which can be located and opened easily from the home screen. It’s also fast to start up from sleep, which is useful for battery-operated laptops that hibernate at the drop of a hat.

Microsoft has even taken a leaf out of Apple’s book by “unbundling” many of its secondary programs. So mail and calendar apps, a video player and photo viewer are all included in the price of Windows 7, but as a separate installation known as Windows Live Essentials. If you want to use alternative versions of any of these, simply opt not to install them. And the influence of a European commission anti-competition judgment is obvious when you are asked for your choice of web browser, rather than having Microsoft’s own Internet Explorer foisted on you.

Windows 7 comes in a bewildering number of options, but most buyers will opt for Home Premium, which costs around £70 (or £150 for a three-user licence). Its clever shortcuts and glossy look alone might make it worth the money for XP users. That said, anyone happy with Vista — and despite its bad reputation, the most recent version runs well on mid- and high-range machines — should probably stay put. Netbook owners running XP might have a problem upgrading, as their computers don’t have built-in optical disk drives and at the moment the only way to install Windows 7 is by disc.

Despite the relief at a successful launch — analysts predict Windows 7 will be on nearly 180m machines by the end of the year — Microsoft will not be breathing easy. More Apple computers were sold over the summer than in any another three-month period, and like Windows 7, Apple’s latest operating system, Snow Leopard, is in many respects a sleeker, back-to-basics version. Google’s Android operating system for smartphones is starting to appear on netbooks, and its free Chrome software for computers will debut next year.

In the face of these encroachments, Windows 7 could be the last major version of Windows to be released. In future, Microsoft is more likely to offer incremental upgrades, which are cheaper to develop. If 7 is the last incarnation of Windows, at least it’s a good one.