After nearly six years in development, Windows Vista has finally been released to the masses.

New PCs will ship with it, those with upgrade vouchers will be cautiously cashing them in and the rest may be left wondering just what, if anything, they’re missing out on.

This latest version of Windows promises much: improved reliability and security, a redesigned user interface and the ability to use new hardware technologies.

You can check out the new interface in our Vista image gallery.

As with Windows XP, Vista comes in various editions. There are two versions aimed at home users, one for business and one Ultimate edition that combines all the features of both. Corporate users will also be able to take advantage of the Enterprise Edition, while the Starter Edition is a version available only in what Microsoft calls emerging markets.

This may seem like a confusingly large number of options compared to the now familiar Home and Professional editions of XP, but let’s not forget Media Center Edition and Tablet PC Edition both of which contained special features now folded into the mainstream versions of Windows Vista.

So for most of us there are no more versions of Vista than there are XP, but there is more choice at retail where Media Center and Tablet PC Editions have not previously been available to buy without a PC.

In fact, this would be true were it not for that fact that all versions of Windows Vista except Starter Edition come in both 32-bit and 64-bit versions. If you buy the full, retail product you’ll get both versions in the box and you’ll have to pick which one you want to install.

See Vista in action in our video review .

Upgrade and OEM versions come with only either a 32-bit or a 64-bit copy. So you’ll have to buy before you try. You can’t upgrade at a later stage.