Realtek 8139
From LinuxMCE
One of the cheapest 10/100 Mbps network cards that can be found. Works very well with LinuxMCE, no extra setup required, unless you want it to boot a diskless machine.
These cards have a socket to install a bootrom, but usually come without one. An alternative way to boot diskless Media Directors is described on the GRUB PXE page, where you can also download a version of GRUB specificly built for use with this particular card.