I got the connector installed fine, but the problem is that WHS can't seem to figure out that this is the same computer and now shows a duplicated 'COMPUTER_NAME' on the server. I don't want this to show up as a new computer as it is the same computer, and I want to keep things historically aligned for retrieving from backups.
How do you get WHS to see that it's the same computer, just a new operating system?
There is no way to do that. WHS does not use the computer name to identify a client (it uses a GUID instead). When you installed the Connector software on your 7 installation, it created a new GUID different from the one that your XP install had.