You wrote in post #6:
"Good to note that my two valid Win XP failed to be recognized as such when installed in new motherboards (few months difference) because of the original ones failed. I realized that the whole SP3 is available somewhere in the Web. I downloaded it and both started to be recognized as the original valid ones."
You seemed to be indicating that you did a hardware change on a registered machine and then XP was no longer recognized as valid.
At that point, it was possibly suggested that you called Microsoft and had them re-activate your license because of a hardware change, but you found it worked when you installed SP3?
Is that correct?
I was indicating that I did a hardware change recently, albeit quite a few years after I had scrapped the machines I originally bought the XP licenses for.
I previously bought the licenses, used the machines, scrapped the machines, XP reached it's EOL and I found I needed XP again - I had already paid twice for two license seats, so instead of calling Microsoft to have them re-activate an EOL OS, I found an XP SP3 download which catered for my needs.