I'd just recomend to the kid to get the same set up I have, I very much like it, and then he will have some change left over to buy a few smaller things from the apple store..
I have 2, 23 inch cinema displays, a powermac quad, and a powerbook 15inch (now he would get the macbook pro) and then final cut studio.. then with a little bit of talent he can turn the money his grandparents gave him by editing videos for people who need videos and while doing this.. saving up for a camera so he can shoot the videos too.. buying alot of things from apple if you have some talent in a field like video or print, then its like investing in yourself, and the harder you work the more money you will make, unlike just dumping it all into apple stock, there is nothing you can do to make the price of apple go up. while you can make your 15,000 more by investing in yourself buying things you can use to make more money, and then you can put that money into the stock market and still have some left over.. I am a strong advocate for not only investing in other companies but also investing in your own talents.