Mobo with onboard NIC and boot rom

Hi. My faculty advisor has asked me to start working on specing out a Beowulf class cluster for the lab, and I need a little help. We already have a pretty sexy linux box that we'll just turn into our head node, but we want dumb-as-a-stump compute nodes to bolster it. I've been reading, and it sounds like in order to build the nodes as diskless units, we need a motherboard that with an onboard boot rom so that we can use a single boot image on the head node. Can most new motherboards be made to do this, or what motherboards specifically can? I'm usually pretty good with computers, but this is somehting that I've just never ran into before, and don't really know what I'm looking for in detail. Thanks!