Vista RC1 Beta here and not Vista Beta 1 as that is no longer supported by M$.
When you downloaded Vista Beta 2 or RC1 you would have been e-mailed a product key that you need to enter to allow Vista to install. If you downloaded Beta 2 and then RC 1 you can use the same product key as M$ didn't supply a different key for these products if you already had the first version.
Now when it comes to the Activation Key this is obtained from M$ by On Line Registration not by entering a Product Key which is something completely different. Even if you don't have an Internet connection to this machine and rang M$ for an activation key a day/week/month ago and made a record of that it will not work as an Activation Key again you'll need to obtain another one directly from the M$ Beta Testing section.
Currently I don't think that the Phone Support for MS Vista Activation exists as this is a Beta copy and expected to be connected to the Internet and run till it breaks or causes problems. It will then report back o M$ the problem that it has experienced so that if it's something new M$ can start work on a fix and if it's a known problem you can be told how to fix the problem of that work on a fix is currently underway.
Col