Rather than hacking up a laptop to do the control, have you considered using something like a Raspberry Pi, Beagle Bone Black, or pcDuino to be your smart processor? You would have to learn Linux (assuming you are coming from a Windows background), but these processors are much smaller/lighter than your normal laptop/netbook and are more setup for embedded work. They typically use a SD card to hold the file system instead of a disk drive, and they don't have a screen built in.
Lets see links for the systems include:
- Raspberry Pi: http://www.raspberrypi.org/ with Pi's available at Element 14, Adafruit, and Sparkfun.
- Beagle Bone Black: BeagleBoard.org - BeagleBone Black. Also available at Mouser, Element 14, Adafruit, etc.
- pcDuino: http://www.pcduino.com/. Also available at sparkfun.
In addition to Linux systems, running Android might be an option. Besides using a smart phone or tablet (possibly jail broken), you can buy Android systems directly, such as the Miniand mk802: https://www.miniand.com/products/MK802%20Android%20Mini%20PC