The immanent arrival of Microsoft Vista is going to present a unique challange for training your business users. Unlike any previous version of Windows, the Vista desktop presents a totally new user interface with a set of program controls that will look foreign to anyone already familiar with Windows.
Probably the best example is Internet Explorer 7.0, and this is something that will also present a downlevel compatibility issue for existing Windows 2000/XP installs. The IE7 user interface is completely devoid of any menu bar, so users that are familiar with traditional menu commands will need to discover a toolbar equivalent for common operations. While some functions such as Print are intuitively highlighted by an icon in the shape of a printer, the button designation for selecting a favorite is not going to be nearly as straightforward.
Additionally, there is the underlying issue of hardware support. While most of your legacy Windows applications should run fine on Vista, esoteric hardware that requires a third party driver needs to wait for Vista support before upgrading. If you had a driver that worked from NT 4.0 all the way to XP, it may not work with Vista and it absolutely will not work with the 64 bit Vista.
IT organizations should plan to start training with IE7 and incrementally train when Office and Vista are subsequently planned for deployment. Training with IE7 has a minimal impact on users and training staff, and provides maximum exposure to the new Windows interface paradigms. This should be timed to cooencide with extensive compaibility testing to ensure IE7 supports the web applications your users require to do their job.
If training is avoided with IE7, most companies will find themselves addressing a windfall of IE7 application support issues. Since IE7 is also a great introduction to the ribbon-based toolbars and the lack of a traditional program menu, organizations will be missing an opportunity to educate users properly for a new GUI interface that will ultimately appear in MS Office 2007 and Vista.