I think she was six at the time.How old was that?
For board/card games, we were doing Munchkin, Dungeon, Ascension and Smash-up when he was 7 1/2, but didn't start D&D (Moldvay) until around 9 1/2.
Oh, and good point about Dungeon. I had already been running games of that for her and her brother for about a year at that point. Dungeon was honestly the gateway drug for me and my brother back in the day and I think it still works great as one today. (It's the original rogue-like!)