If you haven't seen Windows 7 yet or you have the beta version installed, you are running out of time to download the Release Candidate version.
After the 1st July 2009, the Beta version will start rebooting every 2 hours and will stop working entirely on the 1st August 2009. If you want to keep working with Windows 7, you will need to upgrade to the Release Candidate as soon as possible.
After 15th August you will no longer be able to download the Release Candidate. See the post below for more information:
Try it now, Windows 7 is very cool.