The family pack is only for upgrading existing operating systems.
New builds require a full licence, unless you own a full retail version of a previous os that has been removed from a previous pc.
OEM systems are not transferable.
To make things more complicated OEM licence conditions have changed, not to our advantage. Read the post at this link.http://forums.cnet.com/7723-19411_102-374252.html?tag=posts;msg5061256