I think that's a good age to get them started and HeroQuest is one of those games that's great for beginners and can be made more and more complex as needs be if they really get into the whole RPG aspect.
Painted Models and other 'eye candy' are a must when it comes to getting kids attention
Talking of candy, for added try buying a bag of sweets and hand them out at the end of the game for treasure (chocolate coins are ideal) - I've done this with adult players in the past and it always goes down well
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~The ravings of a single mad Goblin is bad enough, but such a power-hungry, malice-filled creature as Mortis can never hope to be understood~