First you need a TV antenna, anything should work, even the simplest rabbit ear. I use a RadioShack box; so I can remotely adjust its direction. I tried many, this box works the best and gets all my channels 40 miles away. You need to try different locations to find the best spot in your house.
Then, you need a HDHomerun, often on sale for $30 or so. You plug the antenna into it and plug it into your router.
Now download the software from Silicondust and watch your favorite shows.
You may watch on an large external monitor via a USB-VGA adapter, CPU load is only a little higher, 32% vs. 12%. Watch and work, at the same time.
If you don't see image but audio only, you need MPEG2 decoder. Search for "CLVDPack080410.rar". During installation, the only item you need to select is "Cyberlink MPEG- 2 decoder (PDVD 10) v18.104.22.1688":
If you want to watch on your Android phones and tablets, you need the InstaTV Pro app, works very well. If you want to record your shows, you need Windows Media Center or MediaPortal.