Here's some food for thought. I've had my Xbox for a couple of years now, and in that time, both the woman of the house and my daughter have had no interest in it. Sure, they watch me play every now and then, but that was really the extent of it.
Yesterday, they saw me playing around with the avatar. My wife then wanted to make her own avatar, which led to her getting her own account on my box, which further led to her checking out the arcade and buying a couple of games ("I didn't know they had Pac-Man! Frogger! Whoa!"). My kid, not content with her own account on my box, now wants one for herself for Christmas.
Funny how that silly little system brings in the casual crowd, eh?