This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
You will need to use the security manager; see the Security Features in Java SE tutorial to start with. This is how applets are prevented from accessing local files, and from using reflection to get around these limits.