Cookie managment software will allow cookies to be deleted routinely.
Firewalls will allow you to control which ports and services are allowed to make a connection to the internet. Closing ports will allow you to deny remote administration clients from connecting to a local server.
The Windows Registry is a file that maintains information on every program on the machine. Watching the Registry can be a good way to determine what processes are running.
These programs allow you to use your PC for secure telephone communications, using a standard crypto algorithm.