I have built one for a customer. Running WMC7, and Dual ATSC tuner it works great!
I certainly can't compete with Magnavox on price, but I can get pretty close ($400)
It allows you to integrate HULU and youtube, and netflix, as well as whatever other internet media service you have interest in.
I installed Classic Archive TV for some of my retired customers. They love watching TV shows from the 50's and 60's (Roy Rogers, Dick Van Dyke, Mary Tyler Moore...)
You don't have to pay service fees, but you do have to have "always on" internet to get guide updates and internet TV.
Unlike the Magnavox, you can record 2 shows at once and watch previously recorded/downloaded movie/DVD/internet TV, or record one and watch another live.
Plus you have the capability to extend it to another TVs in the house with media extenders, or XBox over the home network. And you can add more tuners for more simultaneous recordings (the one we use has 8 tuners, and serves 4 TVs)
6 TV's in the house on FiOS and we only pay $4.99/month to connect them all!!! Power to the CableCard and WMC7!!!