I found ESXi 5.0 needed update 1 to see the Atheros 8151 on my Gigabyte Z77-D3H m/b.
ESXi 5.1 worked fine with net-atl1c-1.0.1.14.x86_64.vib and ESXi customizer.
Using the Intel i7 3770 chip and 32GB RAM as a home lab env.
I found XenServer 6.0 needed additional driver support to see the NIC.