It doesn't necessarily make world of difference. When you compare students who attended top private schools vs. those who were admitted but attended state schools, they actually have equivalent incomes down the line.
What's likely happening is that really smart kids at good state schools end up finding the pockets of talent there anyway.
Pretty scary implications for the value of a Harvard degree.
source: http://www.newyorker.com/archive/2005/10/10/051010crat_atlar...