What kind of Monitor do you have? AFAIK, you wont need a TV Tuner with a HDMI one. And you will be able to watch only the same channel in both TV and PC unless you buy another set top box.
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Appreciate me now and avoid the rush!!
i5 2500K || 8GB DDRIII 1600 MHz RAM || Zotac GTX560Ti || Samsung 2233sw || Corsair GS600