See
http://arstechnica.com/news.ars/post/20061102-8140.html
"
A previous version of the Windows Vista retail license restricted the
number of times you may transfer Vista from one device to another. The
license read: "The first user of the software may reassign the license
to another device one time. If you reassign the license, that other
device becomes the 'licensed device.'"
The new license has removed this language relating to device transfers,
and now reads: "You may install one copy of the software on the licensed
device. You may use the software on up to two processors on that device
at one time. Except as provided in the Storage and Network Use (Ultimate
edition) sections below, you may not use the software on any other device."
"
However:
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It bears repeating, however, the the OEM license that comes with Vista
is indeed similar to the Windows XP OEM license in that it forbids any
kind of transfer. As we have previously reported, users have
nevertheless had success transferring those copies of Windows, but they
are technically stepping outside of the bounds of the EULA when doing so.
"

