Moving our TFS Server to Active Directory wasn't that bad. I followed these instructions from MSDN. They are meant for people moving from one domain to another. But the steps worked for moving from a TFS workgroup based install to a domain based install.
All of the tasks that were assigned to Kyle or myself were migrated over to our new domain usernames and using this handy permissions tool, I was able to get all of our permissions set correctly.
The only problem is initiating a build. When I right click on our Team Build and try to start, it gives me this error:
Access to the path 'C:\tfs...BuildLog.txt' is denied
I'll tackle that one in the morning, it's been a long day.
And I'm also very excited to start using Grant Holliday's TFS Bug Snapper.
Here are the links to Part 1 and Part 2 of this AD Adventure.