I haven't researched it yet, but what about all of these new TVs coming out that are DLNA certified, let you install Web apps, have Google TV built-in, etc? I tried a first-generation HP MediaSmart TV and it was horrible, but I think this new generation is much better. Has anyone tried installing Twonky or something to stream directly to your TV without another machine in the path?
I currently have a couple of machines running Windows 7 Media Center and that works pretty well, but I'd like to get away from Windows. It's also a bit of a pain to watch TV episodes online because the "Internet TV" options inside of Media Center are pathetic, so you have to either go directly to the TV network websites via Web browser or use Hulu or Boxy, so break out the keyboard. There may be third-party applications that you can install to work around this somewhat, but I haven't looked into it.
I'm playing with an XBMC box, but made the mistake of purchasing untested hardware to install it on and haven't worked through all of the issues yet, but the interface looks promising and it is widely used. The wife really doesn't care for the Windows Media Center setup because of its inability to easily stream online content, but I think she will like XBMC if I can ever get this box working right. Of course, I could also resolve 90% of her issues with Media Center if I just recorded or downloaded the content she wants to watch onto unRAID instead of trying to stream it live, but that's a less than ideal workaround for a significant (but understandable) deficiency. I have not tried streaming online content in XBMC yet, so I don't know if it's any better.