>And Microsoft claims OEM software cannot move from another pc. If I throw my old pc, MS says "you have to throw your OS too". I think so that's not legal.

I am in that position now, hopefully it will resolve alright, as it happened to me before and to MS credit they reactivated the OS (I have several computers at home and I am always buying new hardware for them, and after enough hardware has being changed I need to re-activate XP, I will need to do it again this week) and I do not know of anyone that got the reactivation rejected, but you are right, it shouldn't even be mentioned...