VMware ESXi 4.0 Update 1 and Later Installable with vCenter Server 4.0 Update 1 and Later

vSphere Basic System Administration : Virtual Machine Management : Virtual Machine Configuration : Adding New Hardware : Add an Ethernet Adapter (NIC) to a Virtual Machine : Network Adapter Types

Network Adapter Types
When you configure a virtual machine, you can add network adapters (NICs) and specify the adapter type. The type of network adapters that are available depend on the following factors:
The following NIC types are supported: