RegSnap is a tool that can help you analyze changes made to the Windows Registry. Using RegSnap snapshots of registry values can be created and compared. This now only allows for a comparison of what all keys were modified, deleted, and/or added but also furnish system critical information, such as file listings say in Windows System directories. Lucid HTML reports are generated. Alongside .reg files are also generated (these are backups of system registry values) using which the registry changes can be undone and any older/changed version can be applied. RegSnap Pro version supports command line interface, Object Linking and Embedding (OLE) Automation (i.e. it could be accessed and used from within other programs of your choice) and can connect to a remote registry. The 'regedit' alike Graphical User Interface (GUI) allows browsing through saved registry values.

RegSnap Standard vs RegSnap Pro:
RegSnap comes in two different versions, Standard and Professional. Professional version has following additional features over the Standard version (keeping intact all features of standard version) :

Command line mode

OLE Automation support (i.e. RegSnap Pro is scriptable from Visual Basic or any other Automation client)

Remote registry connection

Limitations: 30-day trial.