Thank you for answering my question, the pogo plug is similar to the sheeva plug, see down.
A tablet wont do, too large, I want to plug it in, configure the stuff and rather forget about it physically, it should gather a lot of dust on the outside.
Failing that one, why not get one of those chinese tablets. The Ainol Elf (classic) runs Ubuntu and has 1gig ram. Thre's even a desktop varient which has SATA (but only 512mg)