Enhanced vmxnet

Enable the enhanced vmxnet option when configuring a new virtual machine

* In the New Virtual Machine wizard, on the Choose Guest Operating System page, select the version Microsoft Windows Server 2003, Enterprise Edition (64-bit), even if you will install a different version of the operating system on the virtual machine.
* On the Choose Networks page of the wizard, select the adapter Enhanced vmxnet.
* Proceed through the wizard.
* Install the desired guest operating system on the virtual machine.
* Install VMware Tools on the virtual machine.

Enable the enhanced vmxnet option when configuring an existing virtual machine

* from the VI Client, power off the virtual machine.
* Right-click the virtual machine and select Edit Settings.
* In the Virtual Machine Properties dialog, select the Options tab.
* Click General Options, and change the guest operating system to Microsoft Windows * Server 2003, Enterprise Edition (64-bit).
* Click the Hardware tab, and then select the Network Adapter.
* Click Remove.


taken from http://kb.vmware.com/kb/1007195