Sorry to say been there done that. Its a nightmare and well worth forgetting about, especially as MS have done rather well in protecting their work
After a three turnbacks to those setting out to con you I was put on to a £60 'Student' copy of XP Pro. Sealed box, validation certificate and it loaded just fine. This is it!!
I later had a very nasty crash and had to re-load it three times over a period of months but MS, via the telephone number on the install sequence if things go wrong, were very helpful and understanding. They gave me a new ID's each time and off I went. Never looked back.
It was inevitable that MS were going to protect themselves come what may. I believe they have now done it.