The company also disclosed some of the hardware constraints that Windows 8 tablets will have to follow. To get the new interface, tablets will have to offer a resolution of at least 1024x768. Anything lower and they will be stuck with a derivative of the classic Windows 7 shell. Increasing the resolution from the 4:3 1024x768 to the 16:9 1366x768 will additionally enable the "snap" side-by-side multitasking view that was demonstrated.
Mention was also made of boot performance; UEFI systems with SSDs were described as being able to fully boot, from cold shutdown to the Start screen, in under six seconds. Wake from sleep will be instant.
Microsoft also talked a little about the ARM version's compatibility with Windows. ARM Windows won't include an x86 emulator, and as such will not be able to run existing Windows programs. It is, however, the same operating system with the same APIs, meaning that it should be possible to recompile existing software and device drivers for ARM Windows with few difficulties. The same applications should, therefore, become available on both platforms, as should access to the same hardware.
With Windows 8, Microsoft is paying far more attention to the hardware, and providing far more guidance to hardware manufacturers. For example, the company has recommendations for how large to make the bezels on tablet computers to ensure that they're comfortable to hold. Combined with restrictions on the number of devices that can be brought to market, the message seems clear: Microsoft would rather have a smaller number of best-of-breed devices than the same kind of free-for-all as exists in the world of conventional PCs. (Source