Sandboxie can detect changes on folders and on the system registry, and virtually no software can escape its sandbox. It stores temporary files and the browser history separately. When the session ends, you can decide what to do with the changes caused by browsing the web. Any software that you use through this tool stays equally useful, and keeps working normally.
If you are one of those users who downloads and installs all sorts of things from the Internet without much care, filling your toolbars, having your home page randomly changed and your browser intercepted, it might be a good idea to install Sandboxie. It's not an antivirus or firewall, but in contrast to other sandbox systems that take up lots of resources, Sandboxie lets you keep using your browser as well as any other desktop application.
The software is free, but after 30 days it shows a voluntary registration screen.