It should be pointed out here that geekishness is not limited to computers and related items.
If you have a deep and abiding interest that takes you way into detail and into related fields with the same passion that you show for your primary interest, then you are a geek
Trainspotters who investigate the life of Isambard Kingdom Brunel and steel production methods of the 18th century, Movie fans who know the history of the Oscars and who won the award for best costume design in 1936, cross-stichers who design and make their own patterns based on the tapestries of Versailles, all these are geeks.
I know cat geeks, children's TV geeks, lingerie geeks.
Geekishness is an attitude not a subject.