I thought that VMware was replacing the vClient with the web client, but it seems that this is not the case with standalone ESXi 5.1 hosts! In other words, if you have a standalone host, you have to install the vClient.
Furthermore, if you have multiple ESXi hosts and you want to use the vCenter appliance, you first have to install ESXi, then install the vClient so that you can deploy the vCenter appliance. After all of this you can use the web client to manage your infrastructure and forgo the vClient.
Unless I've overlooked something, VMware this is clumsy! :smileyangry: