Extra Credits, a regular lecture on game industry topics with funny pictures hosted by Penny Arcade addressed this issue a while back. I found it very illuminating.
An anonymous reader writes: The Chosonilbo reports that several government ministries in South Korea are advising users not to install Windows Vista, at least until popular online services can be made compatible. The problem is that ActiveX is pervasive in the Korean webspace, employed by everyone from web games to online banking. Upgrading to Vista is expected to render many of these services unusable. Portions of the popular "Hangul" word processor, a major competitor to Office in that country, are also not functioning under Vista. The Ministry of Information is planning to publish compatibility information for popular websites, and urging users to carefully research the implications of upgrading.