Activation XP

I was just wondering how this works.. I had a problem on my system and after trial and error I tracked it down to a bad stick of memory.
But with all my messing and removing pci cards to track it down WIN XP Pro decided I needed to re- Activate it due to major changes.
So I thought no problem my system was backed up fully with ghost, but when I re ghosted it back to its original state before my problems I still had to go through the activation process.

I thought ghosting a drive wiped it clean ? So why did I have to do this from an image file that XP did not know about !!! I think ?



MJ.