Ask and you shall receive - Exchange 2007 SP3 w/support for Windows Server 2008 R2 Now Available

I had the same issue of "binary files are not installed, but the backup settings registry key is present.  Only build-to-build upgrade mode is available" and I finally figured out that I had to run the command suggested for the SP1 upgrade: setup.com /mode:upgrade and then it would still fail when trying to upgrade each role telling me that the service or one of it's dependents was disabled. When I checked the exchange services, they had ALL been disabled and when I reset them back to automatic and ran the upgrade again, it would again disable all the services as it started each roles upgrade. I finally was able to see the services "disable" as the role upgrade started and if I reset them to "automatic" as each role was being upgraded I finally was able to make it through the upgrade and everything seems to be working correctly. Why, if the service needs to be started at the end of each roles upgrade would the services get disabled at the beginning of the upgrade instead of just stopped? Anyway, I hope this helps someone else.