I have a SD directv box but want to use my computer as the tv. I was told with a tv tuner I would be able to do this. Directv told me to have the channel on my computer to 3 and use the directv remote to change channels. My question is if I have a tv tuner that is also a video capture will I be able to record or do I still have to have a dvr from Directv. I have windows 7 and windows media center.