Apple's KnowledgeBase is a valuable tool for troubleshooting and serves as the official voice of Apple Support. So it's nice to see them tackle the tough subjects sometimes, like "Mac OS X: Locked File Can't Be Moved."

Their solution to this problem: "If you can't move a file because it's locked, unlock it before you move it."

http://docs.info.apple.com/article.html?artnum=25554