I don't think the second would activate. You would probably get a message
that the key was already in use. Read the Vista EULA first chance you get.
It tells you that you can have the product installed on one "device" at a
time and goes on to define a device as a "partition or blade." The emphasis
is on "installed" not running.

You can install as many copies of Vista as you like, but each requires its
own license. When the OS is running is not relevant to the licensing (and
never has been in any version of Windows).

The only license that I recall which references when the software is running
is the Office license, which permits installation on one desktop and one
mobile device assuming that both are not used at the same time.

"Ken" <notforu@sothere.com> wrote in message
news:B89AA427-28F8-4368-8D8A-D2908AA19CCC@microsoft.com...
>
>
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> I was sort of hoping you could have two installs activated on a single
> machine at a time with the one key. I thought this could be possible as
> only one of the installs can be booted at a time if you know what i mean?
>
> So activating the second install would automatically make the first
> install unactivated again?
>
> Ken
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>