Sandboxie

Sandboxie runs your programs in an isolated space which prevents them from making permanent changes to other programs and data on your computer. Running your Web Browser under the protection of Sandboxie means that all malicous software downloaded by the browser is trapped in the sandbox and can be discarded trivially.

It also offers enhanced privancy including: browsing history, cookies and cached temporory files collected while web browsing stay in the sandbox and dont leak into Windows.