The most versatile option would be to assemble a computer of some sort. The Roku and Boxee Box are both going to be limited in their ability to play content and may not be considered “even”.

You repurpose an older machine, assemble the parts yourself, hit the easy button and purchase a complete system from Newegg. Something like the Acer Revo might work nicely for this purpose. You’d be able to watch everything the Roku or Boxee Box could display and a whole lot more.

How old is the child that would be using the system? I would think would be a pretty big factor in your decision.

OTA HD broadchasts are suppose to look even better than the compressed signal we receive from the cable company.