Buying a "used" copy of XP

I've seen several people ( private parties )selling used
copies of XP on E-Bay.
Most say they never installed it ... so O.K.
but..
There are some sellers who say they installed it but
later replaced it with another O.S. Usually XP replaced
with XP Pro. The sellers in these cases claim that it
(the copy of XP) can be sold and re-used since it's no
longer installed on the original or any other computer.

Is this true ? Can I buy a previously installed copy
of XP that is no longer in use and install and activate it
with Microsoft sucessfully?

I've been all over the various Microsoft web-sites,
knoeledge base and such but theres nothing covering re-
activating used copies.

There are a number of these for sale on E-Bay going for
around $50. I have 4 computers at home (wife and kids) so
I'd like to save a few bucks if possible.

Thanks, Mike

"Mike" wrote:

There are some sellers who say they installed it but
later replaced it with another O.S. Usually XP replaced
with XP Pro. The sellers in these cases claim that it
(the copy of XP) can be sold and re-used since it's no
longer installed on the original or any other computer.
Is this true ? Can I buy a previously installed copy
of XP that is no longer in use and install and activate it
with Microsoft sucessfully?

1. Yes.
2. If this is an Upgrade version you need an older Windows version as
well since Upgrade versions do not come with an own Windows license
and cannot be installed without an older Windows installation (or
installation media).
3. You may want to ask for a confirmation that no copy of the CD is
kept by the seller and you should make sure that you get the original
Product Code sticker.
4. If you buy an OEM version or a so-called Recovery CD be aware of
that you may not be able to use the CD on your computer because of a
kind of a dongle that will make most of these CDs only run with the
same hardware with which they had been sold at first.

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