Hi,
you can search for supported NICs here: http://www.vmware.com/resources/compatibility/search.php?deviceCategory=io
If it's just for study, you could also install VMware Player or Workstation (Player is free for nun commercial) and run the vSphere Hypervisor as a VM.
Doesn't give you optimal performance, but for studying it's enough, and you don't need supported hardware for ESXi.
Tim