The Windows 7 RC will fully expire on June 1, 2010. Your PC running the Windows 7 RC will continue shutting down every two hours and your files won’t be saved during shutdown. In addition, your wallpaper will change to a solid black background with a persistent message on your desktop. You’ll also get periodic notifications that Windows isn’t genuine. That means your PC may no longer be able to obtain optional updates or downloads requiring genuine Windows validation.
To avoid interruption, please reinstall a prior version of Windows or move to Windows 7. In either case, you'll need to do a custom (clean) install to replace the RC. As with any clean installation, you'll need to back up your data then reinstall your applications and restore the data.
To qualify for an upgrade version of Windows 7, you need to have been running Windows Vista or Windows XP on the PC you used to test the RC.