The advantage of the via processor line is small footprint, low voltage requirements, and low cooling requirements. I use a via c3 800mhz fanless in my freebsd box at home that is basically a shell server. It suits the purpose, and don't use too much power and gives off almost no noise. I also have an 80w dc-dc power supply for it, but I'm not using it right now, so I could actually make it silent other than the drive spinning.
I previously used a c3 500mhz, moving from 500mhz to 800mhz was quite a difference, especially when generating ssh/ssl keys. Supposedly newer via processor/board combos have a rng built in, but I haven't really looked into if freebsd can interface it and how, but that would speed up key generation quite a bit. Thats the only thing I have really found slow about the vias'.
http://mini-itx.com/ Sells boards and the dc-dc powersupplies, even as a bundle. There is also a company in Austin Tx that sells quite a few of the via boards, but the name escapes me at the moment.