Geek. Nerd. Dork.
Somewhat permissible four-letter words. The Holy Trinity of playground epithets.
In my early 80's childhood, these were synonyms. The Tri-Lambdas were nerds, but they could have just as easily been geeks or dorks.
With the dawn of the NerdASDAQ, the spectacled set became awkward social overlords. Alex Rodriguez may make a lot of money playing baseball -- $25 million per year at the time of this writing -- but he'd have to make that salary for 192 years to have as much money as Bill Gates has right now.
As the keys to the kingdom now come in a nerdy box, people now use the terms geek, nerd, & dork with a greater degree of linguistic accuracy.
Geek now conveys a high degree of interest in a geeky topic. What's a geeky topic? Observe The Geek Hierarchy, grasshopper. (via Ann Maria Bell)
Being called a geek is no longer that bad, unless the term is used by others to describe you to someone you're interested in dating.
However strange it sounds, it appears that Nerd was a term coined by Dr. Seuss. Quite the schoolyard bully, that Seuss.
Nerd still retains some of its grade school nastiness; however, I've found that adults almost exclusively say it in a loving way, with a smile. The most frequent usage of the term is in the phrase, "You are such a nerd!" after you've betrayed a truly geeky personal interest. (Again, refer to The Geek Hierarchy to understand an activity's level of geekiness. You can examine the Frequently Paraprased Questions if you're still baffled.)
Dork is still bad, almost meaner than it was back in the day.
I don't buy Webster's definition, placing dork between nerd and jerk. Show me these jerk nerds. Besides, nerk or jerd would work perfectly well to describe these people.
In the linguistic circles I run in, dork is rapidly becoming the new jerk.
Anyway, none of this may interest you. That is, unless you're a nerdy geek like me.