[Winman]

I agree, I believe Paul was saved when he realized Jesus was the Lord. You see some interesting things here, first Paul asked;

"Who art thou Lord"?

I have a feeling Paul knew who it was, but perhaps not. Then the Lord answered;

"I am Jesus whom thou persecutest: it is hard for thee to kick against the pricks."

I think the very moment Paul heard the name Jesus he was saved. This must have been a terrifying moment for him, as he realized he had been persecuting the people of God and the Lord himself. But Paul surrendered his heart and will to Jesus that very moment and said;

"Lord, what wilt thou have me to do?"

Unlike those who saw and heard Jesus and rejected him, Paul was no fool. And he was a true man who honestly wanted to know God. He surrendered his life to Jesus right then and there.