My wife is supportive to a point with my addiction. (no not the porn)
My wife loves to entertain guest and so the building up of our game room is really something she is supportive of. The best way to suck the wife into this is to have some friends over and let them play and with the banter and comments it will plant a seed in the back of her head. This is especially effective if you can get her friends or the children of the friends into it.
Ask questions... There are tons of chick friendly games that they like as well. My wife is especially fond of trackball games. (centipede, world class bowling, shuffleshot, hamsterball, and feeding frenzy are a few). Centipede was the game that hit her gaming gspot and unlocked a whole new world and acceptance.
If she likes gambling work the angle (slot games, poker games, etc...)
Because of my wifes enjoyment in the hobby (entertaining mostly) the game room is pretty well set up. (arcades, slots, jukebox, pool table, popcorn machine, snow cone machine,etc...)
If you can figure out a way to turn a profit by rolling over some games that sugar coats it for them and helps seal the deal as well.
Good luck
-Goz