We're seeing total overload on our activation servers today so some people haven't been able to get keys to install the new Office or Windows betas. We apologize for that and are working on getting more capacity online. In the meantime you might want to watch the keynotes from WinHEC. Lots of good stuff there.
And keep trying. Hey, I remember when I was a beta tester on Windows 95. I had to download the entire OS on a 28.8 modem! I did that every weekend. How things have changed!