I am a nerd. Nerds in my opinion are the smart ones (Steve Jobs, Bill Gates) book smart, education smart, etc.
The geeks I ALWAYS classified as the poser nerds. Geek is a funnier word, but I would use geek to describe my jock friend who hung out with the nerds as a geek... or anyone who plays Collectible Card Games or MMOs as geeks.
I also feel that people who play mostly MMOs aren't gamers... I'm odd that way, but my arguement is this: Why are they a gamer if they only play one game online for X amount of hours? A gamer in my mind is someone who has no genre bias.
Just my rant for the day... I haven't had one in a week!