I use MyPaint with my Lenovo X201 tablet, it supports touch and stylus input. The machine is connected to a regular projector and my students and I are very satisfied with this.
Here is an example of a discussion about hash functions in Python; it is a screencast where you can see me doing stuff in the terminal as well as sketching explanations on a blank canvas.
MyPaint is cross platform, it is designed for artists and painters, but I am happy with it as a teacher. I used to rely on OneNote in the past, but I've moved away from Windows quite a few years ago and never looked back.