Not quite know what you mean. All TV cards have a window on your desktop.
If you mean PiP on TV. Meaning one main window showing a channel and another child window showing another channel. In this case you need 2 tuners. The TV signal is splitted inside the TV. The child window is overlayed on the screen such as OSD
ok, I guess I was assuming that when you had a regular tv tuner card that you had either that OR the desktop. hehe, I dont even have cable TV, Im not a tv person. I am asking for selling purposes, lol.