Microsoft SMB Community Blog : Regardless of what any hack says, a Windows 7 Upgrade is an Upgrade. What you need to know.: http://blogs.msdn.com/mssmallbiz/archive/2009/10/27/regardless-of-what-any-hack-says-a-windows-7-upgrade-is-an-upgrade-what-you-need-to-know.aspx
Microsoft SMB Community Blog : No, OEM Microsoft Windows licenses cannot be transferred to another PC: http://blogs.msdn.com/mssmallbiz/archive/2009/10/27/no-oem-microsoft-windows-licenses-cannot-be-transferred-to-another-pc.aspx
Already there is buzz about using upgrade media to perform a clean install. "But if Microsoft didn't want us to to it they would block it'.
Wrong. It's there for us that are needing upgrade paths but the upgrade media alone is not a qualifying media to perform an upgrade.