Single Board Computers

Does anyone here have much experience with Single Board Computers (SBC)? The newer 1 to 1.4 GHz AMD Geode or even the dual VIA 1Ghz boards have me considering building a truly silent audio recording / media box, and the 6" square footprint would be great for packing around or even just for stuffing one into my old bus. I'd like to know if such a critter would make good use of an Audigy XFi or M-audio 4x4 for recording live music. Most boards support 1 to 2 GB RAM, have 1 PCI slot and don't require a fan or graphics card. I'm not expecting nose-bleed performance, but the idea of silence and low power consumption has me thinking that these may be a great raw recording unit for home and on the road. I'll still use my home PC for heavy lifting and effects, but a 6 to 14W proc and total power draw of less than 40W for the whole machine has me thinking that I could throw some cheap solar panels on the roof of the bus charging a car battery with a small inverter and have a computer that I could fire up whenever I'm in the bus and feeling inspired or throw it into my cabin that is off the power grid. I know a notebook would do the trick, but I'd like to build one of these because I'm a tweaker and would rather have an inconspicuos box under the dash or shoved into a dark corner of the cabin. Ebay seems to have them in the $100 to $200 range. Any suggestions or experience would be appreciated.