What does "Möhre" mean here? And where does this expression come from?
Vielleicht sollte ich noch hinzufügen, dass unser Windows 7 PC über WLAN am Netz ist, und wir für die alte XP-Möhre ein Netzwerkkabel benutzen.
Möhre here refers to the old computer. Generally, any piece of equipment that is outdated (not in a nostalgic way) and often already insufficient can be referred to as a Möhre.
The word is short for Mohrrübe (carrot). Gurke (cucumber) can be used in just the same way.
Gurke or Möhre is an synonym for an average item, nothing worth paying attention anymore.
An old computer, software or items which is not up to date anymore is just a normal none considerable thing.