A nerd is someone whose life is focused computers and technology. A geek is someone whose life is focused computers and technology, and likes it that way.
That’s close (I’m handcoding the html tags while I write this in an open source notepad replacement), but it misses one other characteristic.
Geeks not only like their life – they are so excited that they want to share it with you.
I like that latter definition much better, because I’ve met wine geeks, opera geeks, movie geeks, music geeks, soap opera geeks… well, you get the idea. Sports geeks abound in the United States.
And that’s what makes the internet awesome.
Geeks don’t just consume culture. We share it (obsessively). We comment and critique it. We remix it. We riff off of it. We create it. 
And that’s what makes the internet so awesome, and so much more than just another delivery system for prepackaged media.