Very similar to the structure of the Pepsi billion-dollar prize, I think.
http://en.wikipedia.org/wiki/Pepsi_Billion_Dollar_Sweepstake...
Most huge cash prizes are annuitized. I went on Who Wants to Be a Millionaire (airing Wednesday) knowing that even if I answered every question correctly, I would at best be looking at a cash value of under $800,000. It's just the way it works, and it's always spelled out in the official rules.