You should purchase a full version to create a dual boot to keep in
accordance with the license agreement. An upgrade license subsumes the
existing one for XP to create the Vista license, meaning you can use only
Vista once the upgrade is complete. The upgrade is cheaper because its use
is validated by the inclusion of your existing XP license. To use both in a
dual boot would require a full license for each, though in a technical sense
there are workarounds.
The upgrade disk differs from previous Windows upgrades in that it must be
started within the existing, running XP or 2000 install in order to enter
the Product Key and proceed. You cannot simply boot from it and "show" it an
XP disk as a qualifier for upgrade.
Best of Luck,
Rick Rogers, aka "Nutcase" - Microsoft MVP
Windows help - www.rickrogers.org
My thoughts http://rick-mvp.blogspot.com
"JJ" <email@example.com> wrote in message
> If I buy Vista (Business) 'updgrade' (I have XP Pro) am I able to keep my
> XP Pro on my pc and install the upgrade on another hard disk on the same
> i.e. I don't wish to run the XP and Vista at the same time, but I do wish
> to keep my XP on the machine in case of compatibility problems with Vista,
> and switch between the two when I need to (dual boot) .
> I wasn't sure if the 'upgrade' software is required to detect and
> overwrite the XP install, or if it just requires that you supply an XP
> install disk during install?
> If the former (or if installing the upgrade somehow 'deactivates' the XP
> Pro) then I'll have to pay more for the 'full' version.
> Thanks in advance,