approach 1 uses a EPIA mini ITX motherboard and DC-DC converter. http://www.mini-itx.com/store/?c=2#p1641
with this sort of motherboard on the bot i would be able to get real time stereo vision working. (no more messy IR sensors for me....)
the main problem with using a PC motherboard is power draw.
using a less powerfull PC would obviously use less power but will still be hugely inefficient. PCs just aren't built with low power draw in mind.
using a 10Ah battery pack i was only able to power my MiniATX motherboard for about 4 hours, despite the motherboard only drawing around 1 Amp. (in theory it should have run for around 10 hours.)
i put this down to the battery pack only being able to supply that sort of high load near the top of it's charge cycle.
using a laptop motherboard would probably be a far more power efficient way of getting lots of on board processing power.
You can always check ebay. They have lots of old laptops for under $100. Some of them are also sold "for parts", and have broken LCDs. You may be able to get 800+ MHz for less than $50 from those defective laptops.
using something other than a microcontroller on you bot will mean you will have to solve the I/O problem. how do you read sensors and switch motors on and off from a standard PC?
i'm using this project to build USB I/O controllers: http://www.obdev.at/products/avrusb/index.html so i'll still need microcontrollers on the bot even with my more advanced processor.
using a serial port or i2c I/O conroller is also an option.
You can always check the Phidget devices (http://www.phidgets.com/
). They have USB interface boards, motor/servo controllers, range finders, accelerometers, all sorts of things. Some of these things are on the expensive side, but it avoids the need for a microcontroller. Their devices are also linux compatible, which is a must for me.
i'm still undecided which processor i'm going to go with. (maybe i'll end up with 2 bots...)
while the PC motherboard is overkill, it lets you do lots of cool stuff with it's somewhat excessive processing power.
the linksys slug on the other hand is a nice compromise between power consumption, while still being able to use PC peripherals and operating system.
the advantage of using USB components and a standard operating system is i can develop the various pieces on my laptop and then plug them into the bot controller once they are working.
even the controller is changeable as they will both run the same linux operating system as my laptop.
I'm definitely going with a PC. My robot will be on the heavy side, but I want to have all the CPU power and all the RAM I can possibly get for visual processing, plus the high speed wireless connection.