Well, I haven't been impressed with people using MPEG4.
Its like watching live TV through plastic food wrap.
If I'm downloading and can't find a 720p .mkv, I'd prefer an old fashioned .avi to an h.264.mp4. Only the YIFI group seems to know what they're doing.
The tuners will have to change, only the carrier is analogue [as Mother Nature is, re:EM spectrum] to accommodate extra digital pulses, then new decoder chips to execute the various functions. Just as my capture cards have hardware MPEG2 decoders [originally designed so they could run in otherwise discarded 386/486/P4 era computers in 2006] and since you could forget about having an RF modulator, would play a DVD's Mpeg2 file directly, up-scaling to whatever your monitor resolution was set for (with DVD43 or AnyDVD installed) all the way to 1080p [well, 1024, since 1080 is a "pass through" setting for TV].

To save my fingers:
[Link: en.wikipedia.org]
[Link: en.wikipedia.org]

I hope I don't get disappointed like I am with MPEG4.
The more you compress a signal, the more you lose in fidelity.