This is what wealth is all about - Choice.<p>Bill and Melinda now have the choice to help millions of people around the world, and they do so.<p>More importantly, their contribution of wealth - even in the form of vaccines worth 50c - means millions of parents now have the choice to spare their children from illness and death.<p>This is what Bill will be remembered for - right now he's the Microsoft founder doing good with his billions, but in 100 years' time, he will be the technology guy who drove vaccines into Africa and saved thousands upon thousands of lives.