I am helping our customers to deploy Windows 7 and to mitigate all application compatibility issues. Since all the users will logon as standard user, so we rely on UAC virtualization (file and registry virtualization) to resolve most of the incompatibilities issues and it works as expected.
Now, customers wish to relocate the user profiles from C:\ to D:\ (I mean relocating the entire user profiles C:\Users, not the user profile folders) and that cause UAC virtualization to fail and hence cause many new application compatibility issues.
We tried many ways to relcate the user profiles, such as using the ProfilesDirectory in unattended.txt or other methods we found from internet. All caused the UAC virtualization to fail.