Hmm. Think I'll look up a second-hand copy on Ebay.
No such thing, once an XP license has been activated it dies with that machine and is not transferable, this would be the case for a "retail OEM" version
Providing the code given with the disk has not been used then why not go for it!!
Incorrect.
Worse case you have to tap a few numbers into the phone keypad to say you've changed the motherboard.
As I said, ms don't care about xp anymore, you used to have to speak to them if you had reached the activation limit, or the hardware had changed. Now it's all done by recorded message.
I used a customers oem xp pro from the bottom of their 5 year old laptop to install on a new pc build, activated with no problems.