Returnil Virtual System Personal Edition is freeware that I highly recommend. It’s virtualization software that mirrors your whole system configuration, and it creates a virtual storage disk where you can save important files and data. Returnil’s system protection features also prevent against malware-driven or accidental unwanted changes, and the whole application is designed to let you just restart your computer to return to an optimized configuration.
I happen to try out a lot of software applications, so one of the benefits of running an application like Returnil is that you can install and try programs in a partitioned environment without worrying about making changes to your overall configuration. I also found performance to be snappy across the board with Returnil.
Of course, if you’re willing to pay a little, VMWare is outstanding virtualization software, and I’ve heard good things from Mac users who run Parallels. These products are widely used by people who want, say, Mac OS X and Windows running on the same system. DeepFreeze is also notable for its editions for Windows, Mac or Linux users. Like Returnil, it’s optimized to let you just reboot to restore a previous system configuration.
I am giving up. I need to see it work but my list here is growing enormously. Fortunately acquisitions are keeping that count down but expect more of such versions in the wild!