MSDN Premium Professional Subscription

Greetings and salutations,

I've just recently started a MSDN Professional subscription.  As part of the
shipment, I received a card concerning "Important and exciting changes to
your MSDN Subscription", providing links concerning the transition from
"MSDN Professional" to "Visual Studio Professional Edition with MSDN
Professional".

On the msdn.mircrosoft.com/howtobuy/vs2005/subscriptions/ page, it states
that a Premium subscription is now available that provides additional tools
(see msdn.microsoft.com/howtobuy/vs2005/subscriptions) but I can't seem to
find out how to upgrade my current subscription to a Premium subscription.
I found where it states that MSDN Professional will automatically be
transitioned to VSPro w/ MSDN Pro, but I'm interested in taking advantage of
the Premium subscription level.

Where can I find information on how to upgrade MSDN Professional to the
Premium subscription and will the upgrade only cost me the $500 difference
between the two levels?

Thank you.