Perhaps because so many people have too much unused memory and hard drive space? They feel a need or compunction to use it all and Vista will come to the rescue since it's such a resource hog.

On a serious note, I doubt if many corporations are going to want to put up with the headaches of upgrading to Vista. Many IT departments are ran pretty conservatively as IT managers are not willing to rock the boat with anything too risky. And nobody but a fool is going to want to buy all new hardware just to run this OS unless they are due for a system upgrade anyway.

I'm going to stick with XP SP2 for a while even if I can get another university deal on Vista. It sounds like something that may be interesting to play around with on a spare hard drive or something but not something I want on all of my systems.