Vista Loosing Popularity!
Many large companies and also universities are changing to Macs. This is the case with my friend's workplace. Their department are changing to Macs. Poor Vista.
Too, the departments that are switching are not to be blamed. The blame is on Vista and also Microsoft. In a one way, setting 4 Vista versions is a good idea, thus it will offer variety of features and choices. However, it is made buying Vista more confusing.
In addition, have a minimum of 1 GB of ram for the top 3 versions of Vista is totally absurd. This means that older machines will not be able to run Vista or your PC will slow down till you can only run a couple of applications at a time.
Microsoft, Vista is a very good product. However, there are a couple of very important issues that you have not solved. And these are causing you to loose your customers.