Philipp Hachtmann wrote:
  So what is the oldest computer still operational?
 In Stuttgart (Germany) I have played lunar lander on a 1958 valve
 computer (LGP30). The machine will have 50 years this year...
 A link (in German, but there is a picture of the actual system though
 it has been repainted later to mint green):
 
http://computermuseum.informatik.uni-stuttgart.de/dev/lgp30/LGP-30.html
 In the ZKM (
www.zkm.de) in Karlsruhe/Germany they have a sometimes
 operational Zuse Z22 from 1958.
 Philipp :-)
 
 I was thinking of the LGP30 when I asked the question. It is small.
Something the size of a house is not going to survive.
Sometimes is good enough for me... It was probably not much better when
it was new.