The same issue occurs that happened with XP. You have the SID issue and then you had the Windows 7 license issues. Unlike XP, 7's license has teeth.
Before Win 7 came out, with win xp, I can ghost one master hard drive then ghost back to 10 identical systems (same cpu, motherboard and video). Then each system will manually enter the product key code. Now with Vista and Win 7, you can ghost it but it will not boot up when installed on the systems. How can I create a master copy on a hard drive, with Win 7, and ghost it to another drive so it will boot up on other systems with the same hardware?