Just to clarify a point, the non operation of printers under Vista was caused by lack of drivers
from the printer manufacturers. Although they had plenty of time to develop drivers for the Vista model, some manufacturers decided not to develop them possibly in an attempt to drive hardware sales
As for iTunes, If apple decide to provide a version of their software to run on Windows it it their responsibility to ensure it works, as it it Microsofts to ensure that their office suite works with a Mac if they wish to sell to that particular market.
A lot of perceived problems with Vista were, and are still being, caused by shoddy programming on the part of 3rd party developers