So I now have VCenter Server installed (5.1) along with the SSO Server and Inventory Server. I have loaded the VSphere Client (5.1) and logged into the client.
I created a datacenter, because it didn't look like I could attach to the 4.1 datacenter.
None of the new hosts had been added, so that was my first task to add the host to the datacenter. When I did, I get this message.
A general system error occurred: Timed waiting for vpxa to start
All the references I read, seem to indicate that this is because the host has one or more VM's associated with it that have too many snapshots.
However, these are new host and they don't have any VM's associated yet.