Well, I wouldn't say you can't outright. True you wouldn't be able to do it through the DVI port. But, you can do it. It's just going to cost a whole lot of money. 🙂 You can get a scan converter to scale down the PC output to get it to go into a video capture card on the Mac, and then you can see the PC output on the Mac screen. Probably not going to be what you want, but it is possible.