It should be noted that the english version of One Piece, licensed by
4kids entertainment and shown on Fox's saturday morning lineup (now called
4kids TV, formerly known as the
FoxBox), is mostly unwatchable due to poor voice work and some very large cuts, edits, and dialogue re-writes. The pleasing, emotional score of the original version has been ditched in favor of a Looney Toons-esque soundtrack that I don't feel really fits the series at all.
It is my recommendation that parties interested in the One Piece series skip the 4kids version of the anime, instead reading the fairly competent graphic novels available from Shonen Jump, or by watching an alternate, perhaps legally ambigous version.