Advice????????(GUYS & GIRLS CAN ANSWER)?

A boy my friends goes to school with saw my pic on aim and thought i was cute. He asked me out twice but I said no because I don't know him & he's younger than me. Now he wants to date my friend and says he's her gf. I'm really happy for her, but the guy still IMs me everytime I sign onto the computer and he always wants to talk. Should I stop IMing him?