“Talk to” and “talk with” are close to each other in meaning, but give slightly different feelings. “Talk to” is very direct. When you say, “I need to talk to you,” the feeling is very business-like; you have something important to talk about. It also means that you will be doing most of the talking and the other person will mostly be listening.
“Talk with” is lighter in tone than “talk to.” When you say, “I need to talk with you,” the feeling is more like you want someone to listen to you and provide feedback. For example, “I need to talk with my doctor.” “Talk with” usually means both you and the other person will be doing talking and listening. If you need to consult someone about something, use “talk with.”