ARM's cleaner design beats Intel's smaller manufacuring process
Intel CPU's have a fast risc core and huge number of transistors to convert X86 instructrutions into risc instructions. ARM (and MIPS) are risc cores, so the do not need to waste transistors and power converting a legacy instruction set into something that can be decoded efficiently.
Intel and Via CPU's use power to get data to and from the north bridge. The north bridge uses power to get data to and from the memory. ARM (and MIPS) CPU's have a memory controller built in like AMD CPU's, so it only takes half the power to get data from memory to the CPU compared to an Intel or Via chipset.
These two advantages more than make up for the better manufacturing processes that Intel uses for Atoms. ARM (and MIPS) give better performance per watt than X86. Also you do not need to pay for the massively over-priced Inhell Inside sticker, so you get better performance per £ too.
The other advantage of ARM (and MIPS) is that closed source software vendors have difficulty supplying multiple variants of their binaries. Stick to open source applications and you can compile them whenever you change architectures (If you are too computer-illiterate to compile programs yourself, Gentoo automates the process for you). You will never have to wait two years and pay an buy the software again like you did when you went from x86 to AMD64.
ARM and MIPS have good economies of scale for devices. If PHB's understood the value of ARM and MIPS, we would see economies of scale for laptops (laptop: a notebook that will not catch fire if you cover the cooling vents by using it on your lap.)