I'm in withdrawal as we speak.
Cold turkey is the only way, man. Quit Civ. Quit the forums. Don't even say the word. If you find yourself thinking about it, MAKE YOURSELF THINK ABOUT SOMETHING ELSE.
This worked for me for about six months leading up to and just after the release of Civ4. Then Christmas vacation came up, a laptop capable of running the game fell into my hands like mana from heaven...and the rest is history.
But it worked for awhile!