Bill - you may only purchase a Retail copy of Windows XP pre-owned. (You
may not transfer an OEM copy - so it is a breach of the license to resell a
used one.)
If you buy a pre-owned Windows XP , you MUST get the Original CD ROM as
well as all other pieces of packaging and license material and the Product
Activation Key.
You should also get a signed letter from the seller stating that they have
removed that copy of Windows XP from any machines it was installed on and
have not retained any copies of the CD ROM or the Product Activation Key.
Finally as with all sale get a written receipt and enough verifiable contact
details that you can retrace the seller at a later date should any further
action be required.

The rights to transfer the licese of Winodws XP are deatiled in the End User
Licese Agreement.(see below)

13. SOFTWARE TRANSFER. Transfer to Third Party. The
initial user of the Software may make a one-time
permanent transfer of this EULA and Software to another
end user, provided the initial user retains no copies of
the Software. This transfer must include all of the
Software (including all component parts, the media and
printed materials, any upgrades, this EULA, and, if
applicable, the Certificate of Authenticity). The
transfer may not be an indirect transfer, such as a
consignment. Prior to the transfer, the end user
receiving the Software must agree to all the EULA terms.

--
Regards,

Mike
--
Mike Brannigan [Microsoft]

This posting is provided "AS IS" with no warranties, and confers no
rights

Please note I cannot respond to e-mailed questions.
Please use these newsgroups

"Bill" <shambler23@yahoo.com> wrote in message
news:0a0f01c33f20$eb4ecfe0$a501280a@phx.gbl...
> Apolgize if this has been posted before. What are the
> rules regarding previously-owend copies of Windows? If I
> purchase or I am given a complete retail copy of windows,
> will I be able to register it and then purchase an upgrade
> later?