If you have purchased a Toshiba computer with Windows Vista Business or 
Windows Vista Ultimate pre-installed, Windows Vista downgrade rights permit 
you to 'downgrade' to any version of Windows XP Professional (including 
Tablet PC Edition & x64 Edition). In this context, downgrade means to 
install and use Windows XP Professional in place of Windows Vista. You may 
downgrade to either a new copy of Windows XP, or to a copy that has already 
been installed (and activated) on another computer.

These downgrade rights are granted by Microsoft Corporation. For further 
information on this topic, contact Microsoft, or visit microsoft.com.

When you downgrade to a previously activated copy of Windows XP, the online 
activation procedure will fail, and you will be prompted to call the 
Microsoft Activation Support Line (866-740-1256). The Support Line staff 
will verify that you have a valid Windows Vista Business or Windows Vista 
Ultimate license and will assist you with the activation of your copy of 
Windows XP

Windows Vista downgrade rights permit you to use either Windows XP or 
Windows Vista on your computer, but not both. The most straightforward way 
to downgrade from Windows Vista to Windows XP is to back up all of your data 
files and documents, format the hard disk drive, and then install Windows 
XP.  Before you downgrade to Windows XP, you may wish to use the software 
(included with some Toshiba computers) that allows you to create recovery 
media, from which you could re-install Windows Vista in the future.

You must possess or obtain your own copy of Windows XP for downgrading. 
Toshiba does not provide copies of Windows XP for this purpose.

Only Windows Vista Business and Windows Vista Ultimate may be downgraded. 
Windows Vista Home Basic and Windows Vista Home Premium may not be 
downgraded.

Windows Vista downgrade rights support downgrading to Windows XP 
Professional only, and not to Windows XP Home, and not to Windows 2000 or 
other earlier versions of the Windows operating system.

Windows Vista downgrade rights also permit you to later re-install your copy 
of Windows Vista -- once you have removed your copy of Windows XP from the 
computer.