Those who have a Beta 2 (build 5384) product key are asked to use it for pre-RC1 build 5536 and RC1 build 5600...it remains valid for the recent CPP builds/releases.
Microsoft did send out the e-mails to CPP participants yesterday shortly after midnight, so you should have received it by now. In short, if you registered for Beta 2 and received a product key (as you have) then you are a CPP participant. Check your spam box and see if it was flagged by mistake.
P.S. Here is the e-mail Microsoft sent out:
"Thank you for participating in the Windows Vista Customer Preview Program. Customer feedback is an integral part of our development process and your continued support is very important to help us improve the overall quality of Windows Vista.
This email is to inform you that the final major pre-release of Windows Vista - Release Candidate 1 (RC1) - is now available for download for CPP participants. Please use the links below to access the download site, and install this release as soon as possible. (If you ordered a DVD kit for Beta 2 you will receive a new DVD kit containing RC1 in approximately 2-4 weeks.)
Important Information about Windows Vista RC1 . We remind you that RC1 is pre-release software and you should not run this on production or mission-critical PCs. Support will be limited to newsgroups, and you may have to do a clean install to move from this release to the final release of Windows Vista.
* You may upgrade an existing installation of Windows Vista Beta 2 or Windows XP to this release. However you will have to do a clean install if you want to get back to a previous configuration.
* Before upgrading from Beta 2 to RC1, please install any Critical Updates from Windows Update for Beta 2. Go to Start, All Programs, Windows Update, and click the "Check for Updates" button.
* Please close any open applications before beginning an upgrade. During installation we recommend you have an active Internet connection and choose to "Go online to get the latest updates for installation."
* Installing RC1 requires a valid Microsoft Product Key. You should use the same Product Key that was provided to you (and sent in email) when you registered for Beta 2 in June. For your convenience, your Product Key is included here:
* Due to the size of the download we recommend you use the download manager provided as it will allow you to resume the download if your Internet connection is interrupted during the process.
* As with Beta 2, the download for RC1 is an ISO file. After you complete the download you will need to burn a DVD to install RC1. For more information, including DVD-burning instructions, program information, and feedback links, please refer to the Customer Preview Program start page.
* To help you explore Windows Vista, we have created a list of tasks for you to try. To access the list and provide feedback on your experience, visit the Windows Vista Scenario Voting site. Windows Vista Scenario Voting
Please use these links to access the download:
Again, thank you for testing Windows Vista. If you experience an error while using RC1, please send the information to us using the built-in Windows Error Reporting technology (a dialog box will display automatically). Sending this information is essential to helping us improve the overall quality of Windows Vista.
We look forward to your feedback.
The Microsoft Windows Vista Team "