In the fog of the datacenter virtualization war, it is difficult to see clearly who will end up on top, and yet the outcome is almost certainly determined, and the victorious generals are even now moving on to fight new battles. Here at the Virtualization Practice we too would like to think we can see through the fog to work out who has won, so here are our thoughts, take account of them as you wish. They concern, primarily, the big four protagonists: Microsoft/Hyper-V, Citrix /Xen, VMware/vSphere and Red Hat/KVM.