being a denizen of the digitial age, the preferred dictionary of choice is obviously--dictionary.com or en.wikipedia.org
From wikipedia:-
Traditionally, the designation
nerd applies to a very intelligent but lonely and socially awkward
person, one fascinated by
knowledge, especially
science. Beginning in the late
1990s, many nerds on the
Internet reclaimed the word
nerd as a badge of pride, and began using it as a positive description of any technically competent person, with less implication or focus on social awkwardness.
A
geek is a person who is fascinated, perhaps obsessively, by
technology and
imagination.
Dictionary.com has both nerd and geek as:-
A person who is single-minded or accomplished in scientific or technical pursuits but is felt to be socially inept.
in the first place who came up with such a term? it stinks of Hollywood conspiracy, probably the term was invented by some sour grapes directors who cannot stand the fact that he/she is indeed more stupid and hence decided to make a movie out of it. "Revenge of the Nerds", remember? protraying smart people as square, wearing black rimmed spectacles. Get a life, don't stereotype.