I would try and use it as a doorway into the entertainment business and act or sing.
I would buy all the Video Games, CD's, and DVD's, and everything else that I want.
And later buy a nice size house when I was ready to live on my own. I don't know if I would drop out of college or not.
is it comprehensible.....
Hmmm. A billion. A nice amount, but big time plans would burn it up pretty quickly.
Happy/content - plans - big house, tidy investments, continue uni/collage till I have all the doctorates I could ever want - live comfortably for the rest of my life, have enough to provide for my family - I probably wouldn't give up work, but with a sizable little nest egg it would allow greater flexibility.
or
Big Plans - turn that Billion into 100 Billion then double that again and again, strangle the oil industry and microsoft by offering better alternatives, in fact create a corporation that covers, dominates, monopolises various high profit industries and has its fingers in pies the world over. Maybe go into weapon R&D, keeping the best advancements for personal use of course.
Then mess up economies by flooding stockmarkets and so forth, in the chaos raise a mercenary army from all the underpaid soldiers of the world (a problem now, let alone in a time of economic crisee.) From there bribe my way to leadership or conquer various strategic nations, starting with Australia as it's nice and isolated, perfect for my seat of government. Then, using my corporation's/Empire's money, tech etc standardise the tech level of nations I control, promote liberal attitudes and intellect and raise living standards, in order make people want to be a part of what would hopefully be a pleasant little empire....
And from then, it would be a simple matter of assimilating the rest of the world. When it's all done I would then retire to a nice little estate in England, because I'm not greedy. Ahhhh.... A man can dream, can't he?