This is an extremely rugged 2.5" 20gb PATA hard drive. Designed for reliable 24/7 operation in extreme conditions. Withstands shock, vibration, altitude, and extreme temperature variations that would kill a normal hard drive. The model number is ST940814AM, and more information can be found here:
http://www.seagate.com/www/en-us/pro...s/ee25_series/
Still under manufacturer's warranty until 2011. Perfect for carpc. Asking price $50.