We've had really good success with Magic Maze Kids - as well as Ticket to Ride: First Journey and Catan Junior (both of which are fantastic). The thing that Magic Maze Kids has going for it is an _absolutely fabulous_ tutorial system that slowly introduces every mechanic of the game.
Other games like Pigasus and Snowman Dice (both by Brain Games I think) have been a hit too.
Other games like Pigasus and Snowman Dice (both by Brain Games I think) have been a hit too.