Hey Jeremy, hope this fixes it for you!
If you are building a lab at home using Workstation 10 you will probably want to install more than one NIC. However, unlike in Workstation 7,8 and 9 there is a trick to getting the extra NICs to show up on the nested host.
If you install the NICs using Customize Hardware when you build the VM or by powering off the VM after it is installed and adding the NICs. you’ll notice ESXi only recognizes the first NIC.
The trick is to add the NICs while the VM is up and running, then reboot.
Voila, the extra NICs are there.