Make Our Big Flat Panel Our Computer

If the DSBPI's tiny iPod can hold 40gb of music, why cant our giant flat panel TV hold 400gb of movies? (Note: DSBPI has a 20gb iPod and no flat panel TV, but you get our point.) If Apple can fit a whole computer behind the screen of an iMac, why doesn't that computer (but with a 42" monitor) just become our home theater? If Microsoft is developing a portable media-center that can hold hours of TV in one tiny package, why don't we have that on a much larger scale -- in one package?

We want our data, traveling over cable, and our audio/video traveling over cable to terminate in one place. Namely, we want our iTunes and Movielink and HBO-On-Demand in one place (well, actually in many places, but also in this place). We want it on our big, flat screen.