For the people that do not understand how you can be addicted to WoW and not games like CS/COD/Fifa 09. Its because WoW Isnt a game where you just tap random buttons quicker and faster to win or hold down the mouse button to spray your opponent with lead.
WoW is a game that uses your mind, essentially. You will fight against other humans, using your knowledge and quick reactions to determine what abilities you have to counter the abilities your oponent is using. Thats why warcraft does filter out alot of idiots that can be found on Fifa/MOH/COD etc. On warcraft you dont get 'OMFG! I FUKKING KILLED YOU NOOOOB! LOL!) well, unless your on a swedish server; you might find that.
I played WoW starting 2006, for about a year a good few hours a week. At one point I did raid (MC/BWL/ZG etc) and was a Guild Officer and Warrior Class Leader. This guild was a semi-casual raiding guild. We put down bosses, but not every night. I was addicted for say a year? But it died down, and now; 2009. I still go back every now and then for a little pop. And I believe it is the only game I will ever continue to play. It has everything. Intelligence, skill, exporation and excitement.
The reason people do not get addicted to games like fifa/CS or COD is because it is not as interactive as WoW. Your not dependent on other people to better your character. And in those previously mentioned games, you quit the game, save and your ready for the next go. Warcraft is ever changing, the best way to describe it is at its own fantasy little world. You wont know unless you have played it and have say got past level 20-30 to actually witness the game.
Edit - FOR THE HORDE!