Well I'm not exactly sure if this is the cheapest route but you may want to look into this. CETON makes a pci-e express cable card solution. And what you do is you buy a card. http://www.newegg.com/Product/Product.aspx?Item=N82E16815706001
and you obtain a cable card through the cable/satellite company if they offer them. And pretty much what you do by doing this is eliminate your need for a cable box you don't need a fancy box with a DVR because what you can do is have your PC be your DVR. The only thing you would need to have your TV work with this is a media extender like a xbox 360. You save money over time because you don't have to pay for a DVR and you eliminate the cost of a cable box.
A little video explaining it http://www.youtube.com/watch?v=0MEBHVjIu_o