Question : Any tools to monitor registry and program changes on remote computer?

Need to monitor some Windows 2003 servers which are in different workgroups. Here is the goal:
1. monitor registry change on remote computer
2. monitor file/folder chang on remote computer. should have the capability of focusing on partition/folder/file level.
3. automatic scan the above and notify (by email) of any change found.
4. Able to encode the credential for each server in the toll if needed.

Q#1. Can you recommend any (free or inexpensive) tools?

Thanks.

Answer : Any tools to monitor registry and program changes on remote computer?

Registry monitoring type programs, has one:
http://www.devicelock.com/arm/

This one states it can files as well:
http://registry-monitor.qarchive.org/