naja wenn jemand mal neu nen xp pro aufsetzt kann er doch mal versuchen ob xp pro auch den vista ultimate key schluckt...
@ micro entweder oder.. also darfst nicht beides zeitgleich mit dem "selben" key am laufen haben... entweder xp oder vista..
naja geht z.b auch um firmen welche ja tablet PC´s nutzen und da gibt es ja die software auch bald nimmer mehr....
Auszug von microsoft.com
Can I downgrade my OEM version of Windows Vista Business to Windows XP Professional?
Yes. OEM downgrade rights for desktop PC operating systems apply to Windows Vista Business and Windows Vista Ultimate as stated in the License Terms.
Please note, OEM downgrade versions of Windows Vista Business and Windows Vista Ultimate are limited to Windows XP Professional (including Windows XP Tablet PC Edition and Windows XP x64 Edition).
End users can use the following media for their downgrade: Volume Licensing media (provided the end user has a Volume Licensing agreement), retail (FPP), or system builder hologram CD (provided the software is acquired in accordance with the Microsoft OEM System Builder License).
Use of the downgraded operating system is governed by the Windows Vista Business License Terms, and the end user cannot use both the downgrade operating system and Windows Vista Business. There are no downgrade rights granted for Windows Vista Home Basic or Windows Vista Home Premium.
"Downgrade rights are not granted under FPP system licenses."
"Rights to OEM versions of systems software are granted in the OEM License Terms.
The OEM License Terms for most OEM versions of systems software do not grant downgrade rights. The exception is the OEM License Terms for the Windows® XP Professional operating system and the Windows Vista™ Business and Windows Vista Ultimate operating systems, which grant downgrade rights. See the full text of the OEM License Terms for the specific downgrade rights."
"If I have Windows Vista Enterprise, what can I downgrade to?
Downgrade rights in the Volume Licensing programs provide customers with the right to downgrade to any prior version of the same product. Windows Vista Enterprise is a new type of product and does not have a prior version. However, customers licensed for use of Windows Vista Enterprise are licensed for Windows Vista Business, and it can be downgraded to the Windows XP Professional, Windows 2000 Professional, Windows NT® 4.0, Windows NT 3.51, Windows 98, or Windows 95 operating system.
You would not, however, be able to downgrade to Windows Vista Home Basic or Windows Vista Home Premium, Microsoft Windows XP Home Edition, or Microsoft Windows Millennium as those are different products and not considered previous versions of Windows Vista Business."