I've almost finished the build of my Johnny 5 (yes I'm slow, but I've a four-month old baby!), and am currently awaiting some nice 6V 2800mah NimH and 11.1V 3000mah Lipo batteries to finish off the power side of things. Comparable to the Pico ITX Johnny 5 build on these forums, I'm intending to put a small x86-compatible motherboard on the chassis of my robot. I've a 3.5" "SBC" form factor Wafer-5820 board, but feel it will be too underpowered for running Flowstone/Roborealm/etc. (it's a Cyrix MediaGX ~ 266Mhz CPU with 128MB RAM max).
Having used Mini ITX VIA EPIA boards previously, I like their reliability but not their performance and features. The Pico ITX boards, which have rarely been revised and continue to perform poorly, continue to command $300 - 500, which is very rich for what you get.
Unpertubed, I've found a good compromise: a larger 3.5" SBC form factor (which will fit in the rear bottom deck of the Lynxmotion Tracked Chassis with no issues), but with considerably better performance and features, a Jetway NF33-270-LF: http://www.jetway.com.tw/jw/ipcboard_vi ... F33-270-LF
Here you get a 1.6Ghz Atom CPU, GMA950 graphics, Mini-PCI slot, CF slot, IDE, SATA, LVDS connector, and runs directly off 12V AC power supply ... for about $170. Reading through the manual, it also suggests the Atom can be overclocked, noting many hit 2Ghz without issue.
I've enquired and the unit ships with a full-size heatsink on top (no fan), yet is only 30mm in height - perfect!
Anyhoo, thought others might like to know about this find - I'm going to order mine soon, it might even be the first Lynxmotion robot equipped as a Hackintosh