The ProgramData setting specifies the path to the program data folder.
Important:
These settings should be used only in a test environment. By changing the default location of the user profile directories or program data folders to a volume other than the System volume, you will not be able to service your Windows installation. Any updates, fixes, or service packs will fail to be applied to the installation. Microsoft does not recommend that you change the location of the user profile directories or program data folders.
Caution:
Using the ProgramData setting to redirect folders to a drive other than the system volume blocks upgrades.
Reference: http://support.microsoft.com/kb/949977
