Regshot is a tiny open source portable registry comparison tool. It allows a user to take a snapshot of the system registry and compare any registry modifications made after doing system changes or installing new software. The detailed report contains a list of all registry modifications or changes between the two snapshots and can be exported in either text or HTML format. This application requires 300KB for installation.
Regshot - Portable Registry Snapshot Tool:
Authors Website: Regshot
Download: Get this Portable Registry analysis tool HERE