"I have my Product key which was fetched by a program I used,"
This and your story is typical of those that don't own a copy of XP but have been getting by without (somehow.) The new activation has teeth so unless you have the real license it should fail. If you have the real CD, license then a call to MS is needed for a new CDKEY.
I have a home-built PC, built by my father a few years ago. I have Windows XP Professional running on this machine, but since it was installed by someone else, I do not have the disc; because of this, when an error called for recovery, I used an XP Home disc, and everything seemed to work fine. However, I got a new mobo+cpu for christmas, and it's time to change motherboards. I understand I cannot change motherboards without reinstalling or 'validating' Windows, but will this Home disc work? If it doesn't, what am I going to do? I have my Product key which was fetched by a program I used, but I'm afraid that won't be enough to solve the Windows problem..
My current board is (at least it says on the board-) an ABIT NF7. My new one is an ABIT KN9.
AMD Athlon XP 2500+ 1.83 Ghz.
1.12Ghz DDR RAM.
80Gb IDE HDD.