Hi Bryan,
Windows 7 x64 is still in a Pending state for Enterprise Vault 8.0, but it will not be supported by Enterprise Vault 2007 like you on. I would suggest looking at upgrading Enterprise Vault to v8 before you do your role out of Windows 7. But on that not it is still not in the comp guide, just pending.
For the latest compatibility charts please see this link ftp.support.veritas.com/pub/support/products/Exchange_Mailbox_Archiving_Unit/276547.pdf
As for the Release notes and technotes, you cannot subscribe as far as I know, but take a look at this link it contains all the manuals and technotes http://seer.support.veritas.com/docs/277782.htm