I am interested in using one of my pcs as an additional tv and pvr. I know you need a tv tuner card. There are cards ranging in prices from $25 to $200. Some cards says pvr and other just say tv tuner. The ladder is cheaper. Which should I buy? I know I need some sort of additional software like snapstream and SageTV. Can I buy any tv tuner card that takes in my cable signal and use one of those software to turn it into a pvr or do I have to have a specific card that says pvr? Finally what is the difference between a card that says pvr and one that just says tv tuner?