Thanks to Hurricane Sandy, we did a lot of research on trees and neighbors. Unfortunately, if a neighbor's tree falls on your property, it's now your problem, responsibility, and insurance that legally owns the situation. That said, it would be nice if a neighbor (the original owner of the tree) volunteers to share cost and/or labor of tree removal.
I'd go over and talk about the tree damage. You may have to ask up front if they can help with removal or damage, and hopefully they will volunteer to do so. It sounds like they are good neighbors, and I hope they'll volunteer to help you. Good luck!