There's one great mobo for it but the videopart isn't that great. (PCI might help ??). Check this mobo: http://www.viavpsd.com/product/epia_...herboardId=21.
The mobo's aren't that expensive and are all you need for an appliance. (onboard x86 cpu is included)
If you want something bigger look at this mobo: http://www.fic.com.tw/motherboards/at31/at31_intro.htm
(ati radeon based). The chipset is part ATI and part VIA and all features are availible on linux (even opensource) I think.