Pope's take on the name of a saint or saints as do many preists and nuns. He still has his "legal" name, but as Pope, he calls upon saints to help him in his duties, whom he wishes to emmulate or otherwise embrace the qualities they are known for. We do the same thing, as Catholics, when we are Confirmed and take a Confirmation Name.

Whenever I hear Pope Benedict I think of Benedict Arnold. I think they should have gone with a better name...

The tradition dates back to when servants of God took on a new name to coincide with their new mission. For example, Abram/Abraham, Saul/Paul, Simon/Peter, etc.

He could have. The pope has the right to choose whatever name he wishes. This includes keeping his own if he wishes.

No Pope is obligated to change his name. This is a pious tradition (not Sacred Tradition). The practice arose when a pagan convert to Christianity became Pope and changed his name from Mercury (after the pagan Roman god) to John II in 533 C.E. Until then, the Popes kept their original names, from Peter (#1) to Boniface II (#55). Between John II (#56) and Sergius IV (#142) in 1009 C.E. only a few Popes changed their names. But since Sergius IV, it has been common practice for all Popes to change their name when elected pontiff except Adrian VI and Marcellus II. Pope Benedict XVI chose the name Benedict for several reasons. At his papal audience on April 27, 2005, he explained his motivations for adopting the name. “I want to call myself Benedict XVI to bind myself to the venerated Pope Benedict XV, who guided the church in a troubled period because of the First World War. He was a courageous and authentic prophet of peace and worked with valiant courage first to prevent the drama of war and then to limit its nefarious consequences. In his footsteps, I want to place my ministry at the service of reconciliation and harmony among individuals and peoples, deeply convinced that the great good of peace is, first of all, a gift of God, a fragile and precious gift to invoke, safeguard and build day after day with the help of everyone.” Benedict XVI also said he chose the name to evoke the spirit of Saint Benedict, the founder of Western monasticism whose influence helped spread Christianity over Europe. “St. Benedict is very venerated in Germany, particularly in Bavaria, my homeland. He is a basic point of reference for the unity of Europe and a strong reminder of the undeniable Christian roots of its culture and civilization.” http://www.usccb.org/comm/popebenedictxvi/namebenedict.shtml http://www.newadvent.org/cathen/12260a.htm With love in Christ.