In Europe a direct upgrade from Windows Vista to Windows 7 will not be possible.
Windows 7: No direct upgrade from Vista in Europe
It seems like the steps taken by the European Union against Microsoft are now affecting the users. It is said that the upgrade option from Windows Vista to Windows 7 will not be available in Europe because the special versions of the new operating system require a clean installation.
According to TGDaily Microsoft will release a special E version without Internet Explorer 8 and an N version without Internet Explorer 8 and Windows Media Player. Those versions of Windows 7 will be sold in Europe only and won't be compatible to the direct update from Vista. Thus European users will have to save all their files, programs and what not and copy them back on their system after installing Windows 7.
A statement from Microsoft concerning the matter is expected later today. It is yet unclear if and how the free upgrades for Vista PC that had been planned earlier will be available in Europe.