Who was St. Valentine?

On this overly commercialized day of celebrating romantic love, the original meaning is almost completely lost. Just who was St. Valentine and why do we celebrate him? There have been multiple stories of saints named Valentine, but two possible stories have stood out. Both portray the man as a martyr in a story worth celebrating.
Story #1: Around 270 A.D., Emperor Claudius II was struggling to grow his army. He felt that married men made poorer soldiers because they didn't want to leave their wives and families behind. Therefore, he declared a law making marriage illegal so that men would stay single and be more willing to go to war, thereby making better soldiers. A priest named Valentine decided he wouldn't have it and married couples in secret. The emperor found out and had him arrested. Upon meeting him, the emperor actually liked Valentine and offered him his freedom if Valentine would only convert to paganism. Valentine, being a faithful priest, turned the tables and asked if the emperor would become a Christian. This didn't work out because it infuriated the emperor, who had him beheaded soon after on February 14.
Story #2: Around the same time, Christians were heavily persecuted, being sent to prisons where they were often beaten and killed. They were often stoned in the Coliseum, in fact. A priest named Valentine would help them escape their possibly grim fates. Unfortunately, he met an equally grim fate of beheading for his actions.
Side note: Some stories blend the two, saying that Valentine secretly married Christian couples that were escaping persecution. A romantic, although unlikely, twist to the story says that while Valentine was in jail awaiting execution he met and fell in love with a girl, possibly the jailer's daughter. Before his death, he supposedly wrote her a letter signed "from your Valentine," the first Valentine card.