Tiny Watcher monitors sensitive areas of Windows system and allows you to spot newly added programs and other files types (customizable), as well as added registry entries.
Tiny Watcher performs an initial scan of your system to generate a list of current items, and then notifies you whenever a new item is found.
Is Tiny Watcher good for you?
It is small: Uses tiny resources on your machine. Runs fast, and only when you request it.
It is complete: Detects most of the changes that can happen in your system. No need for updates or upgrades.
It is configurable: Various settings can be modified to suit your needs. You can edit the list of directories and registry keys that are monitored, decide which files will be checked, etc.
It is free: Just download, install, and use as long as you want. No adware, no spyware.
It works: Tiny Watcher has been tested and bugfixed with care.

Detects changes afterward: It will not prevent your system from being modified or corrupted. It will only tell you that something suspicious happened. Think of it as an early CAT scan against system tumors.
No automatic cleanup feature: There is no "Fix that for me" button or other magic feature. You have to search the Web by yourself for specific information about a problem, and then do your own cleanup.
Not a novice tool: Tiny Watcher does not tell you when a change is "normal". If you understand little about how a computer works, Tiny Watcher is probably not good for you. Messages will probably make you worry for nothing.

The license of this software is Freeware, you can free download and free use this system monitor software.