"speed bump" converting Vista to Win XP

A few days ago I posted in the "converting Vista
to Windows XP" thread, in this forum. I related
just how tremendous the post was, and how easy it
went for us. When it looked like nothing could
stop the "train", something unexpected came up.
When we tried to activate the Windows XP, we got
the message "this product key has reached the
alloted number of activations." It would not allow
the XP to be activated. We tried using the key on
the bottom of the new HP laptop, and another key
from someone else's XP, but neither worked. At the
same time as this extensive Vista to XP conversion,
I was also working on the home PC, which uses the
exact same Windows XP key, and it also needed to
be activated. After the laptop trouble above, I
tried to activate the home PC, and to my amazement,
the exact same key worked perfectly this time. My
son ended up calling the microsoft number and
activating it over the phone, thru one of those
automated voices. The only thing I can figure is
that part of the activation process is a comparison
of the XP release to the hardware/architecture of
the PC. The XP is the 2002 version, and the laptop
is only a 3 month old model. The house unit is the
old AMD Duron, which is around 2002 or so. Thank
goodness for a kind "automated voice" from MSN!

Dave