Sorry, nevermind, I think I found my own answer.
In vSphere 5.5, the embedded database provided with the vCenter Server Appliance supports an inventory with a maximum of 100 hosts and 3000 virtual machines.
In vSphere 5.0/5.1, the embedded database provided with the vCenter Server Appliance supports an inventory with a maximum of 5 hosts and 50 virtual machines. The embedded database is not configured to manage an inventory that contains more than 5 hosts and 50 virtual machines.
VMware KB: Minimum requirements for the VMware vCenter Server 5.x Appliance