but don't be in a rush - the download will be available until the end of June.
If you're running Windows Vista you can upgrade directly to the Windows 7 Release Candidate, but if you're running the previously-available beta version of Windows 7 you'll need to do a fresh install. This means that you must backup all your data files before starting the install, and of course you'll have to reinstall all your software applications afterwards.
It's a step that requires careful planning before you start. make sure you have all your software installation CDs and product keys, and of course you'll need to check to see that the software will run in Windows 7. You should also investigate the hardware driver situation, otherwise you might end up with a shiny new Windows 7 RC installation and no functioning printer or scanner.