The Supreme Court case that brought Madalyn Murray O'Hair to fame is actually known as Abington v. Schempp and Murray v. Curlett. The court case began with Ellery Schempp in August, 1958; Murray's case did not start until 1960, and her case was built upon the brief filed earlier by the ACLU on behalf of the Schempp family. The SC's decision was given in June, 1963.
One noticeable difference between the two cases was that Ellery as a boy of 16 began a protest against school-sponsored Bible-readings and prayer in 1956; he wrote to the ACLU in Philadelphia and got his parents to support him. Murray filed her suit on behalf of her two sons, Bill and Garth, who were about 10 and 8 at the time. Bill later disavowed his mother and became an evangelical Christian. Garth was murdered with his mother and Madalyn's adopted granddaughter, Robin, whose father was Bill.
Murray's contribution was thus not to the issue of devotional Scripture reading and prayer in public schools but to establishing a permanent voice for atheists. (The Schempps were non-believers of a sort, and they attended a Unitarian church which was non-Christian and humanist.) Unfortunately, Murray's vision of a united non-believer community under AA was lost with the rise of splinter groups, such as American Humanists, Freedom from Religion, Secular Student Alliance, the Secular Coalition, Military Religious Freedom, and numerous smaller groups. FFRF is now the largest group with about 25,000 members, whereas AHA and AA have about 14,000 each.