hminh,
You are correct! In order to backup the data from your computers, a small program we call the "Protection Agent" must be installed.
Once installed, it runs in the background and you do not have to manage or interact with it in anyway.
If you have any more questions, feel free to ask, or sign up for a free 30 day trial at http://www.spn.com .
Thanks!
Richard Goodwin
SPN Product Management