You have two choices:
1. Windows Steadystate: http://www.microsoft.com/downloads/en/details.aspx?familyid=d077a52d-93e9-4b02-bd95-9d770ccdb431&displaylang=en
"SteadyState Helps Make it Easier to Manage Your Shared Computers. Shared computers are commonly found in schools, Internet and gaming cafés, libraries, and community centers. It is increasingly common for owners, teachers, or non-technical personnel to manage shared computers in addition to their many other responsibilities.
Managing shared computers can be difficult, technically challenging, time-consuming, and expensive. And what’s more, without system restrictions and protections, users can inadvertently change the desktop appearance, reconfigure system settings, and introduce unwanted software, viruses, and other harmful programs. Repairing damaged shared computers can require significant time and effort.
User privacy is also an issue for shared computer environments. Shared computers often use shared user accounts that make Internet history, saved documents, and cached Web pages available to subsequent users.
Windows SteadyState provides a more effective way to help defend shared computers from changes by untrusted users and unwanted software installations. It can also help safeguard system resources."
or
2. Comodo Time Machine: http://www.comodo.com/home/data-storage-encryption/data-recovery.php
"Comodo Time Machine (CTM) is a powerful system rollback utility that allows users to quickly restore their computers to an earlier point in time. CTM 'snapshots' are a complete record of your entire system (including the registry, critical operating system files and user created documents).
Schedule automatic snapshots to be taken at regular intervals
Roll back to the last known working state in the event of virus attacks or crashes
Take snapshots of your computer before large installations or system maintenance
Software Developers and testers can easily restore test systems to the default configuration after each deployment without the need to manually uninstall each application. Home users can even let the kids run amok on the family PC for an afternoon and be safe in the knowledge that any damage can be instantly undone and all files recovered.
Comodo Time Machine features an intuitive, friendly interface which offers quick and easy access to all functionality in the application. Additionally, it also features a sub-console that can be accessed before Windows starts and a Quick Operation console containing shortcuts to important and commonly executed tasks."