Petascale Urban Computing - weaving supercomputer networks through the city (vinay.howtolivewiki.com)

Hmm, this fits the bill as far as the 1GHz CPU and 1GB RAM... fairly trivial to add a 1TB hard drive: http://www.extremetech.com/computing/146765-amd-launches-giz...

However, at $200 without the hardrive, it gets a bit pricy.