Here is some simple information about the Windows 7 release candidate (RC) which you need to know if you want to install.
x86 version - 2.47 GB
x64 version - 3.2 GB
Windows 7 Beta Product key will not work in RC build. So you'll need to obtain a new Product key which is available in your account page.
Windows 7 RC will expire on March 1, 2010. At this time the system will reboot every two hours. The license of windows 7 RC will expire June 1, 2010.
You can either upgrade from a Windows Vista system, or do a custom (clean) installation of Windows 7 RC. Windows 7 Beta users will need to do a custom (clean) installation.
Windows XP users will also need to do a custom (clean) installation.