The Windows 7 RC trial was available for free for users to test the new operating system before the actual release of the OS. Many people have used this version to try the OS or have switched to it from Windows XP.
The Windows 7 trail will start automatic restart every 2 hours from March 11, 2010. You can still work with this option till June 1, 2010. When the computer does an automatic restart it will not save any data.
From June 1, Windows 7 RC will boot into a black desktop and users will be shown a Windows Activation screen.
Microsoft has also made it known that RC users will not be able to upgrade to a Windows 7 retail installation. The operating system will have to be uninstalled and reinstalled again with the retail package.
How to Extend the Windows 7 Activation trial period
Darkassasin from the seven forums has a solution to extend the activation period by 120 days. It involves saving an XML file with some code, importing the file using task scheduler and then rearming the activation using “slmgr.vbs -rearm”. Read his post for all the steps.