Ping!
Mohammed couldn't just disregard Jesus, however, for he was too important. So he cleverly managed to make only the followers of Jesus evil while elevating Jesus to the rank of a prophet.
Mohammed had to convince people that Jesus was not the Son the God. If Jesus was the promised Messiah, there would have been no need for another prophet and no need for Mohammed because the prophecy would have been fulfilled.
The problem with this argument is, Jesus IS either the Son of God or He is a liar. To claim He was a prophet but also a liar just doesn't make sense.
Jesus teaches love and forgiveness and died so that we can receive forgiveness and salvation...if we choose to. Mohammed teaches hatred and revenge and his followers are really victims of a cult with no free will at all.