Toolwiz Time Freeze is a free instant system protection tool that will protect your system from any unwanted changes and malicious activity in low disk level. Toolwiz also has a complete, all in one suite called Toolwiz Care.
VirtualBox is a free virtualizer that extends your existing computer's capabilities so that it can run multiple operating systems in virtual machines at the same time. VirtualBox Extension Pack also available.
VMware Workstation allows you to run any virtual machine on their computer. Used by MajorGeeks to test software safely. Unlike the free VMWare Workstation Player this allows you to save and delete snapshots, additional tools and more.