Between the security improvements, the new interface and the major improvements for notebook users Windows Vista looks appealing, but are you going to feel happy about paying for it? You can add some of the underlying technology to Windows XP but there's no way to upgrade to the extra security.

Here we're looking at the Business version, which has all the networking features plus full image-based backup. There are no home entertainment features, no parental controls, but oddly, no BitLocker encryption either - it's only available in the Ultimate Edition.

Are the security improvements enough to switch for or is the rest of Vista enough to make the price tag - for the upgrade and for any hardware you'll need - feel like good value?

With so many versions, the answer is a mixed bag. So let's look at all the different features and versions to see whether you need to upgrade, whether you want to upgrade and what to pick if you do.

You only install Vista once on most PCs but the experience is still critical. Our test installations included upgrading from Vista RC1 and clean installations on a newly formatted hard disk.

Installing Vista

The update installation was, as expected, quite slow, and took nearly two hours. Microsoft spent a lot of the beta process investigating the update method and held install fests in the US to help track down upgrade issues. The result is a smoother update experience, with little in the way of problems.

You will need plenty of disk space free, as Vista's image-based install copies all the required files to your hard disk, before rebooting your system to start the installation. We would still recommend a clean install. For one thing, it's a lot quicker, and there's no worrying whether some legacy application or driver may stop your system from operating properly.

One key test of any new OS is application compatibility. Early versions of Vista had problems with some applications; but we found everything we installed on our test machines ran without problems. This included applications that crashed or failed to run even on Vista release candidates.