First of all, I'm sorry to read that you had a problem with the upgrade on that PC.
The upgrade was staged yesterday afternoon and most people will not have encountered any problems except perhaps the dialogs that annoyed you (and others).
The reason that the Urgent status to configure backup was set on the upgrade is that the backup process changed in 2.0 and requires users to define their backup plan or no backups will take place. Since you (like me) don't use OneCare backup, it should be a simple matter to uncheck the box to turn on backup on this PC.
The prompt about the Hub should not have caused any issues, it is a new feature of OneCare and the dialog was designed to inform you of your options with this functionality.
I don't know what you tried before you uninstalled OneCare from that PC or if the only problem after the restart was a network connectivity issue, so I can't tell you what to try. I suspect that you may have been able to resolve the problem by opening OneCare and clicking on the Change Settings and configuring the network to be Home or Work instead of a public network, but there may have been more involved.
If you plan to reinstall OneCare and run into problems, post back or contact support for further help.
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
-steve