What about the Apostles' Creed? Isn't that one actually more Ecumenical? I know that the Eastern and Western churches disagree on the Nicene Creed, particularly on the "filioque" clause (the Eastern Orthodox version of the Nicene Creed only says that the Holy Ghost "proceedeth from the Father..." (i.e. not "and the Son").
That's an interesting question. The Catechism of the Catholic Church devotes one of four parts to the apostle's creed. However, the essence of the faith is contained in both creeds.
"I know that the Eastern and Western churches disagree on the Nicene Creed, particularly on the "filioque" clause (the Eastern Orthodox version of the Nicene Creed only says that the Holy Ghost "proceedeth from the Father..." (i.e. not "and the Son")."
Well, not quite. The Orthodox "version" as you say, is the one the Nicene Fathers wrote and adopted. The Western version with the filioque is much later. There is no disagreement between the Orthodox Church and the Western Church on what the Nicene/Constantinopolitan Creed says. The disagreement used to be about whether or not the filioque addition was heresy. That's not much of an issue now since the Roman Church has agreed that the Creed without the filioque is normative.