Excellent series on Tradition and the Missals of Pius V and Paul VI

John Hunwicke (Fr Hunwicke's Liturgical Notes), a former anglican clergyman now hoping for ordination as a priest in the Ordinariate of Our Lady of Walsingham and a liturgical scholar has written a great series of posts on "Ratzinger and Liturgical Law." He explainst that the Pope is the servant of Tradition, that a form of Liturgy that has had centuries of usage simply cannot be abrogated by the Pope, and so he explains how Pope Benedict XVI was able to say that the Missal of Pius V (as modified by Pope John XXIII in 1962) was not abrogated by Pope Paul VI.

Even if you are not a liturgical scholar yourself, I urge you to read carefully these excellent articles (and don't worry about the Latin):

Ratzinger on Liturgical Law (1)
Ratzinger on Liturgical Law (2)
Ratzinger on Liturgical Law (3)
Ratzinger on Liturgical Law (4)
Ratzinger on Liturgical Law (5)

And do keep John in your prayers.