Highly functional virtual machine software for safe browsing and for application testing. It is free, but feature-wise pretty comparable to commercial solutions like VMWare Workstation. Still lacks reliable virtual 3D graphics support, though. It is free, therefore 5 stars from me.
I have used all the virtualization products available on the market, free and paid alike. Although this does not equal the same features as VmWare, it comes closer than the other free products.
