Jim,
OK now I understand what you were asking, which I did not understand before :)
As a general rule, we do not support in-place upgrades from Beta to RTM for Exchange unless you are on the TAP program or the Beta program specifically said that this would be supported. If you are on the TAP program, then we work closely with you to have a supported way of going from Beta to RTM in production.
Now - the reason why this is is kind of simple - and comes from the fact that there is no support for Beta in production environment in the 1st place unless you are on the TAP program to begin with.
So I will answer you by asking - you are not installing this in production, right? And if it is a lab, then installing a new org should not be a problem? :)
Seeing that the Beta of E2007 SP1 at this time is not a open Beta accessible to all, we do not have a place to discuss those issues as of now - that might change in the future though.