If you already have a Playstation 3 or XBox 360, then you're already able to do a lot of things that the Roku provides (Netflix, HBO Go, etc.). Even if you don't subscribe to any of those services, a Playstation or XBox 360 are great when you use them in tandem with something like PlayOn and/or Tversity. I use PlayOn, and it allows me to not only stream files from my PC to anything on my local network. What's great about it is that you don't have to worry if your PS3 or 360 will transcode the files (I'm looking at you, MKVs) as the PC does all of the work. It'll also stream it across the internet allowing me to watch things on my phone/tablet/etc when I'm not at home. The Liftetime license for PlayOn is currently $40, so I would jump on that if it suits your needs.
However, if you're looking to record stuff over-the-air, then an HTPC is the way to go.
Heavy is good, heavy is reliable. If it doesn't work, you can always hit them with it.