My kids are 3 and 5, and we've come up with a fairly equitable solution.
Off the gaming room, we revamped my wife's sewing room to include a couch, a VCR, and all the kids movies'. That way, the kids are near to hand, and out of trouble while we play. They've hit a fairly independant age, so it's easier than it was when they were younger.
The only problem is my son, being 5, wants to play too. I keep reading him The Hobbit at bedtime, and emphasize that learning to read will let him play D&D when he's older.