I think VGA is only there for prototyping purposes. This tablet probably doesn't have the power to output a very good resolution or decode high quality video for your LCD TV. You're better off getting a cheap computer and sticking MythTV on it.
On the other hand, I would be a little surprised if the final version did have VGA out.
The MacBook Air can't even play HD video without stuttering. How does your Eee hold up?