I have used the VIA Rhine-ll Ethernet with-out any problems on 9 motherboards(all of them same type) for netbooting (PXE)Clusterknoppix nodes. They also have a Wake-on-Lan feature works well.
When I was looking for a netbootable MotherBoard. The words to look for was "ethernet lan support". Maybe it is more to do with how well the MB manafacture implements the hardware.