Alright so I got a chance to play with this a bit more on my GA-Z77X-UD5H...
First off I used a tool called ESXi Customizer to install a VIB for the Intel onboard NIC.
http://v-front.blogspot.com/p/esxi-customizer.html
Using this VIB that I found on a forum: http://dl.dropbox.com/u/27246203/E1001E.tgz
Once I did this I was able to boot into ESXi and install it just fine.
As far as passthrough goes, it give me options but I've been having a hell of a time to get VGA passthrough to work. The only thing I got to passthrough perfectly was a USB root hub which allowed me connect USB devices directly to a few select ports and they went directly to the VM.
I'm still playing with VGA passthrough but running into weird errors depending on how much RAM I assign the VM. Seems like anything over about 1GB throws errors when passthrough is configured.
I'll keep playing with this and post back if I have more success. So far I corrupted some drivers in my win 7 x64 install so I'm installing a fresh copy as I type this. I'll make sure I take a snapshot this time around.