Just an update: I bought the AverTV Hybrid Volar Max - Windows Starter Kit (what a name, eh?). It is a TV Tuner that connects to your PC (compatible with Windows 7 and Windows 8) via USB 2.0, then you can plug either a coaxial cable into the other end and either stream cable television or OTA (over-the-air) digital television from an antenna to your PC using Windows Media Center (free with Windows 7, $99 for Windows 8, $9 for Windows 8 Pro). This is my first time every using Windows Media Center and I'm really impressed with it: not only is it great for picture and movie viewing, but the live TV function and DVR function are amazing! It's a pity they didn't include Windows Media Center with Windows 8 for free. I have Windows 8 Pro so I didn't mind too much the $9 upgrade to buy it, but for Windows 8 users the $99 is exorbitant (although, that also comes with other features like Bitlocker).
On my HDTV streaming OTA digital cable (from an antenna), I don't get a guide like satellite or cable users have, so there is no way to know what's on (although, I found that there are actually two helpful Windows Phone apps for this: BuddyTV is one, Fast TV Listings is another). But, if you watch live TV through Windows Media Center there is a fantastic on-air guide with all the TV listings, program info, etc. Windows Media Center also allows you to toggle on and off closed captioning, pause live TV and, of course, record TV and watch it later. It really is quite amazing.
After I plugged in the AverMedia USB TV Tuner, it installed the driver automatically, then I went to Windows Media Center and set up live TV by having it scan for channels. And within minutes I was watching TV on my computer. What I did after that was connect my computer to my HDTV via HDMI and got to watch live TV on my HDTV, which I could already do, of course, but this time it had a DVR capabilities, live-TV pausing, and the live-TV listings guide! I also tested it with a VGA connection instead of HDMI and was equally impressed with the picture quality, although unlike HDMI a VGA connection cannot bring the sound over to the TV too, just the picture, so you'd need to get speakers unless your laptop speakers are super awesome.
After that I installed the PC Remote Pro app to both my Windows Phone and my Surface RT. These apps both allow you to connect to a PC on the same WiFi network and control it with fully mouse and keyboard input using the touchscreens on your phone or tablet. Better yet, though, they also come with built-in Windows Media Center controls (like an app within an app) so you can easily control your new TV setup! What I'm going to do now is find an older laptop with Windows Media Center on it and set it up so that it still runs with the lid closed, and then just use it like a set top box: a DVR and 'cable' box so I can enjoy most of the benefits of cable TV without the price!