The ESXi 5.1 iso does not include our NIC drivers, so we have to add them using a slipstream tool.
Use your original ESXi 5.1 ISO and the NIC driver to create a 'customized' install ISO which includes the NIC driver.
The ESXi Customizer was found here: http://www.v-front.de/p/esxi-customizer.html
The driver ( net-atl1e-1.0.1.14.x86_64.vib) was found here: http://www.aligrant.com/?p=news/archive&v=2012-03
The log file I posted was included with the end result ISO file.
I used the new ISO to install to a USB thumb drive, and it works well. Only needed 1gb USB space.
Also added Openfiler v2.99 as a VM to create shared storage. (NFS share or iSCSI)
Added disks (physical RDM) for Openfiler using: http://vm-help.com/esx40i/SATA_RDMs.php
Added another ESXi host and created a cluster for my home lab.