I have both a PC laptop and a mac laptop.
I usually work with both but I have only one of those Microsoft Natural Keyboards, and I sometimes switching between the two machines but I hate to have to switch positions to work on my mac.
I friend mention a nice tool for windows: Mouse without Borders https://www.microsoft.com/en-us/garage/profiles/mouse-without-borders/
This tool is great for windows. But i wanted something similar for my mac and PC. And I found this: http://www.keyboard-and-mouse-sharing.com
I fully recommend it. It has a free version so just try it out.