What you need to do, like others have suggested, is if you have an Intel Mac, get Boot Camp or VMWare Fusion or Parallels and have it emulated and show your dad that the Mac can be a PC.
If you have a PPC Mac, get Virtual PC 🙂rolleyes: ) or VNC and have it connect to your dad's PC and say, look! WINDOWS ON A MAC!!!
If he still doesn't like you, buy a bunch of his favorite iTunes songs he doesn't have and tell him to listen to them and transfer them to his Zune. 😎