Many people reported serious problems by updating there existing Windows XP (TM) machines to Vista (TM).
Even on brand new machines. See for example: http://www.youtube.com/watch?v=FVbf9tOGwno
So many people planed to switch to Mac OS/X but still need WinXP up and running on there existing machine. See http://www.apple.com/switch
One solution is to have in the mean time the same Look & Feel for your XP.
Check the two screen shots. Before and after.
- Is Vista a copy of Mac? Check this: http://www.youtube.com/watch?v=vZ28p-J40d0
- Mac OS X being used over Vista description http://www.youtube.com/watch?v=sTeP_eh8XAA
- See also this: "User Interface Design (Alan Kay Video - Part II)" on http://webcast.berkeley.edu/course_details.php?seriesid=1906978389 (Why not only the user inferface is, what counts. It's also on what the GUI is built on. See at 40:00 for the conclusion.)