I think the majority of people who prefer XP over Vista is because of the difference in the software approach of the Window's explorer file listing system, UAC controls and it's incompatability with older software.
Including myself, I am confused on the Vista search methods & software installations. It seems to take a few more steps in Vista to install software or find a file in a specific directory. There are times when I know a file exists on my hard drive, but Vista returns a "No files found" message.
This is what frustrates most people with Vista.
It's like a person has been riding a bicycle for years, and suddenly Microsoft hand's you a Unicycle. And they tell you it's the same thing but the only difference is that it's missing a wheel. They never tell you you have to learn how to ride all over again. Plus most workplaces will not let you take the time to get familar with the new OS, they expect you to know it inside/out at first touch.