Technofile:  Microsoft has finally launched Windows Vista after about three million years in development (okay, so five years), and the verdict so far? Slick, but possibly not so slick that you would give up the likes of Windows XP just yet.

First of all, you may need new hardware to run it. Vista is vastly more complex than any previous version of Windows, so to make use of its newest features you will need a fairly well specified PC. Microsoft recommends machines have at least 512mb of RAM (although this is probably on the low side), an 800mhz processor and 15gb of hard disk space.

So, with more than 100 million computers predicted to be using it within 12 months, what are the pros for Vista?

Bill Gates claims Vista is "dramatically more secure", sports an improved graphical interface and desktop search tools. And some security analysts have praised these.

Microsoft has pledged to continue support for XP users until 2011, so you can make the transition at your own pace.

However, here are some reasons not to bother upgrading yet. Firstly it'll cost more - twice as much in Europe as in the US. Prices range from €150 for an upgrade version of the Basic package to €375 for a copy of the upgrade to the Ultimate version.

Vista's enhanced security features make it sound not unlike the paranoid, controlling HAL 9000 in the movie 2000AD.

For instance, if it finds that a driver or device attached to the PC is "defective" (which might happen to an older piece of equipment), Vista will literally "revoke" it's access to the PC, turning that faithful old printer into a large doorstop. Quite how this happens and to what devices is still sketchy.

For high-end users, such as programmers, there are some functions you are used to on pre-Vista Windows which may not work. And Vista's mechanism for protecting the copyright on digital content could get in the way of you actually playing some of that content, like music or video.

Vista is also sensitive to hackers and is designed to restart its systems if it detects an "attack". The trouble is that odd bits of data within the system or some flaky wiring - common in lots of PCs which are made by hundreds of different manufacturers - could look like a hacker attack to Vista. Unfortunately it's users like us who will find out how our older PCs will react.

Over at Apple, the only viable alternative for the average user, the company is sharpening its sword with a new version of its operating system. Its equivalent to Vista, Leopard, will be out in a few months.

As with any new software, there is always the question of whether you want to be a guinea pig. Computer security researchers at Trend Micro say prices among cybercriminals for the codes giving access to an alleged security flaw in the first version of Vista are currently running at up to $50,000 (€38,000).

Which makes me think I might wait a little longer before upgrading.