@Jos_SLTN Are you cheating ;-)
VMware vSphere 4 Upgrade Center
Before starting down the path to VMware vSphere, it is worth taking some time to determine what your current VMware Infrastructure deployment scenario looks like with respect to the setup of VMware vCenter and how it is configured to support VI3 Clusters with Resource Pools, VMware HA and VMware DRS. Here we present a mapping of the supported VMware Infrastructure deployment scenarios with respect to VMware vCenter and storage for your boot volume and virtual machine datastores. The tactical steps that you will follow for the three phases associated with the VMware vSphere migration will be identical for all the deployment scenarios depicted in the diagram.
Find out more here