That's why it may be such a costly error for Microsoft to make the Vista upgrade such a confusing mess.

Until today, even experts couldn't tell you off the top of their heads the differences between each of the many Vista versions -- or even how many versions there are -- or what the basic requirements are for the Upgrade versions. Ordinary consumers are baffled to the point of paralysis.

I'm going to clear all this up in a minute. First, however, let's recall the fiasco that is the Windows Vista launch.

The Upgrade version mess

News organizations have been writing about Vista for years. In the past few months, the media addressed Upgrade versions (less expensive versions of the operating system available to users who already have a recent version of Windows), and the process Microsoft would impose for proving that you own a legitimate copy of Windows XP or 2000.