Yeahhhhh call me a cynic, but people who register to give glowing reviews of products as their first post always make me uncomfortable.
Box is running XBMC/Kodi, which you can run on your PC/laptop if you have a convenient way to hook it up to your TV. As to claims about live sports and especially "movies still in the theatre," the sources of these are shady at best, and more realistically mostly illegal/pirate. You can download Kodi and go through all the add ons at no cost to you to see if it *really* meets your needs. I suspect you will find it does not. Great piece of software, and it's not Kodi's fault that there's not enough real streaming content sources. I run it for my own local video collection.
I used to work on a competing piece of open source software to XBMC/Kodi, and actually wrote an modular online streaming plugin for it. There's just not enough legitimate content to make it a true TV replacement over something like Sling TV, which looks pretty promising.