It looks like Jimmie R. Houts over at serverfault has the answer I am looking for. He referenced this article with more information.
To expand on his answer, after installing windows 7:
1. You boot with the install media.
2. At the screen with the "Install Now" choose "Repair your computer"
3. You will be asked if you want to "Repair and Restart" by the System Recovery options, choose "No".
4. Then Make sure that Windows 7 is listed as one of the installed OS's available for recovery, it's selected and them press next.
5. You will be given a list of recovery tools, chose "Command Prompt".
6. In the command prompt you will be using Robocopy to copy c:\Users to d:\Users
7. Type robocopy c:\Users d:\Users /mir /xj
8. /mir tells robocopy to mirror the directories, this will copy all files and permissions.
9. /xj is very important, this tells robocopy not to follow junction points. If you forget this, you will have a lot of trouble.
10. Make sure no files failed to copy (FAILED column = 0).
11. Remove the old Users Folder from the c: drive: rmdir /S /Q C:\Users
12. Create a NTFS Junction that points to the new Users folder: mklink /J C:\Users D:\Users
Now restart and there you go. No further configuration or fiddling required. New user profiles will all be stored on the d: drive, as will any user specific data. And it is achievable without any messing about in the registry, searching and replacing values, or having to mess with new profiles in any way. Totally fire and forget.