On Windows Calibre makes use of three locations -
- the location in which it is installed. 64 bit default - C:\Program Files\Calibre2, 32 bit default - C:\Program Files (X86)\Calibre2
- the configuration data (global preferences, plugins, resource overrides etc) - default C:\Users\<USERNAME>\AppData\Roaming\calibre
This can be accessed from within calibre via - Preferences->Miscellaneous->Open calibre configuration folder.
- the library folders - the default library is located at C:\Users\<USERNAME>Calibre Library, others are wherever you put them
Calibre makes very limited use of the Windows Registry.
BR