Arguments: The numbers were estimated by looking at the development from 2000 until 2007 and Moore's Law
Discussion: In 2014, will there still be a Home-PC like we know it today, or will there be a central server, that is accessed from different devices, including your "PC" or your entertainment-system in the living room?
Current development: Apple TV - access content in ITunes on your Computer from the living room Sonos - listen to your music in every room
The future of our entertainment at home will be a central server in the broom closet. No more pc environment in living- or sleepingrooms. This is the vision of my diploma work. if you're intrested in this projet, stay tuned
Space seems reasonable, but not the 40Ghz processor. The latest trend in microprocessor development is parallel processing, where a single processor contains many cores running in parallel. You can buy 4 and 6 core processors now running at 3.2Ghz (3.2Ghz * 6 = 19.2Ghz power, but only if you're using software designed to take advantage of this). As software developers start writing more parallel software, it'll be more beneficial to reduce the speed slightly to decrease power consumption and heat and increase the number of cores instead.
So my educated guess would be we'll see processors along the line of 16-core 2Ghz.