I have found the same problem at a notebook, i have also read something on the microsoft site about pirating and i think that that is the problem that some hardware suppliers got a security that only the software they supply with the hardware can be installed. I have tried to install WIN XP PRO SP2 onto the notebook, which had a recovery cdrom with WIN XP home SP1. The notebook is from the brand MEDION. If someone knows how to bypass this problem just let me know.