Windows 8 on ARM Will Require Deeper Integration
Windows 8 on a tablet may take more work than Windows 8 on a PC.
While Windows 8 will still find itself home in x86 and x64 desktops and laptops, it will be a major foray into the ARM-based device space. ARM chips are what power nearly all of today's major smartphones and tablets, and that's an area that Microsoft wants Windows to invade.
Windows 8 will most certainly be there, but it'll require a bit more effort on the part system designers.
"Windows 8 running on ARM will ultimately be available with ARM-based hardware that you can purchase," said Windows president Steven Sinofsky. "ARM requires a deeper level of integrated engineering between hardware and software, as each ARM device is unique, and Windows allows this uniqueness to shine through."
Regarding developer tools, Sinfosky added, "The new development tools enable you to start today to build Metro style applications that will seamlessly run on x86 (32 and 64 bit) or ARM architectures. Even if you use native C/C++ code, these tools will enable Metro style apps to target specific hardware if you choose. As new PCs become available for testing, PC manufacturers will develop seed programs for developers."
Impressively, everything Microsoft is showcasing at Build will also run on ARM-based Windows 8 systems. Microsoft appears to be making a big effort in delivering a cohesive Windows 8 experience regardless of platform.

Is there any news on how Microsoft is going to get around the compatibility issues concerning x86 software running on the ARM instruction set?
*spoiler* (it's supposed to do more then make fart sounds, and play iTunes)
Desktop software on a 10" touchscreen is completely useless.
Tablets need purpose made software.
64-bit.
x86 is 32-bit.
You just want a laptop or a netbook, then? Nobody's stopping you my friend!
Get the Toshiba Thrive. USB, SD card, HDMI ports are full size. It's a little thicker and heavier than other tablets, but it's also more versatile.
He's just teasing because 64 bit is also x86. So it should technically x86-32bit or x86-64bit.
that thrive actually looks pretty sexy
Standard x86 processors with integrated ARM cores.
Think about it; with simple tasks like web browzing and word processing you could shut off the x86 portions and save a ton of power.
When you need a little more processing power, or you are working with non ARM optimized applications, power up the x86 cores and gate off the ARM section.
Especially with mobile computing, on the fly switching between x86 and ARM cores could conceivably extend battery life quite a bit.
Why couldn't the compiler produce a single executable containing code for BOTH (that Windows 8 would choose from depending whether it runs on ARM or x86)?
Must be the way in which the code functions at the hardware level. Windows 8 probably will be able to differentiate where it's being installed, but to do that on individual programs would make them pretty big and complicated to code. At least, that's my understanding.
Why do they have to at all?
Do you really want every executable on your computer to be twice as big? Because that's what you're asking for. I think it's a much better solution for the user to just download the appropriate file. It's not like it's hard.
As a side note, I'm shocked at the consistent lack of knowledge about technical areas like these on Toms Hardware. No, Microsoft doesn't need to make the x86 instruction set run on ARM.
What they're doing is putting an ARM compiler on the x86 platform. Then all you have to do is click the ARM entry under target platform, and bam, you just ported your software over to ARM. Somehow making ARM understand x86 instructions, or writing a wrapper to translate the opcodes is about the worst possible way I could think to solve this problem.