Likewise, there is no point in putting one of those stone circles on your Honda when pneumatic tires are available. :)
Home automation isn't new, and there is a ton of hardware and software specifically designed for it. Cocoontech is a great source of information just like mp3car is.
To answer your amplifier question, typically, A is designed for surround sound, and b is for multi room. Either one will work fine by them selves, but you typically can't run surround sound and multi room at the same time.
LINUX MCE is based on Ubuntu and will do what you are looking for.
Watch your pocketbook, and after you get in to it, you wonder why you ever thought you would have to "go to the screen.... then go back to the couch."