You can do all of this and a whole lot more with a PC already.
Right, including a remote control with 48 buttons, and the usual security headaches. Apple's remote has six buttons, and it's simply a better system.
Here is Apple's web page which describes Front Row 1.0 - link.
Apple also has an excellent demonstration of Front Row on a streaming video.
You can do it on a Mac already, too.
But the point is packaging it into a small, quiet, affordable computer that the average consumer can run as easily as any other applicance, such as a DVR. I don't believe the PC or the current Mac setup qualifies yet.