RegistryProt is a 100% free, standalone, compact, low-level realtime registry monitor and protector, that adds another dimension to Windows security and intrusion detection. By monitoring important locations and keys in the Windows system registry, RegistryProt will alert whenever a key is added or changed, and then give the option of accepting the key change, reverting back to the original key setting, or deleting the key.
RegistryProt's most useful attribute is that it will detect the vast majority of trojans at the exact moment that they infect/install themselves into your system, and as such provides a new dimension in trojan and intrusion detection.