Microsoft is expected to release Windows 10 Consumer Preview next month. In the press event scheduled to happen in Jan, Microsoft is also expected to reveal all the consumer features of Windows 10. As previously announced, Windows 10’s hardware requirements remains same as Windows 8.1/Windows 7. However, you need certain updates in the OS before you can upgrade to Windows 10 preview. In order to make things simpler for consumers, Microsoft has released Windows 10 Preparation Tool. This tool will check whether user has supported OS such as Windows 7 SP1 or Windows 8.1 Update installed. It also checks whether the language user has currently installed is available in Windows 10 preview. If everything is ok, then the the tool creates the following key in your PC’s registry:
Value under that key named “Signup” with its data set to “924EADEB-2472-490D-9203-5D0A1FD5CC73”
I guess this will mark the system as Windows 10 preview upgradeable and it Windows 10 installer will make use of it.