HKLM\SYSTEM\
The Disk subkey still appears in the registry of some computers that were upgraded from Windows NT 4.0 and earlier, but the contents are ignored by Windows 2000.
In Windows NT 4.0 and earlier, the Disk subkey contained information about all physical disk drives, logical partitions of disk drives, CD-ROM drives, and network drive mappings on the computer. In Windows 2000, the Disk subkey is eliminated and similar information is stored in HKLM\SYSTEM\MountedDevices.