Sandboxie - 2.1

Sandboxie allows you to run your browser, or any other program, so that all changes that result from the usage are kept in a sandbox environment, which can then be deleted later. This allows you to remove traces of your internet or PC activities, as well as reverse any changes to your Favorites, home page, registry and more. Even files that were downloaded during a sandbox session will be wiped after the sandbox is cleared. The program runs in the system tray and if you want to start a sandboxed session, simply launch your browser, or any other program via the tray icon, rather than the regular way.

Sandboxie changes the rules such that write operations do not make it back to your hard disk.Sandboxie intercepts changes to both your files and registry settings, making it virtually impossible for any software to reach outside the sandbox.
Sandboxie traps cached browser items into the sandbox as a by-product of normal operation, so when you throw away the sandbox, all the history records and other side-effects of your browsing disappear as well.