One of the questions I get asked a lot, even in social situations, is "can you get me a beta copy of Vista and/or Office 2007".
If you're an MSDN subscriber then you'll already have Vista of course (but not Office), but if you aren't then you won't be able to get it yet.
We'll be releasing public betas soon and one of the best ways to find out exactly when is to sign up for the "beta experience" here: http://www.microsoft.com/betaexperience. You'll get a regular newsletter with product info, and will be notified as soon as the betas are available.
Note that you'll be able to order the kits to be posted to you (for a small fee, but stay tuned, we'll be sending a few thousand out free in the UK) or you can download them.
So sign up and we'll wing you an email when they're available.