Since the software giant announced its next windows OS version, Windows 8, can run on both X86 architecture (similar to your legacy PC) and ARM-based devices (similar to your tablet, smartphone,..).
Microsoft has raised much confusion on its legacy apps shown on ARM-based powered tablets with touch interface.
Familiar apps such Word, Excel, PowerPoint, Internet Explorer, etc.. were demonstrated. Ones would think, there will be an emulation built-in to allow legacy apps to run on more power efficient and touch-enabled devices. In reality, based on an article posted by Steven Sinofsky on the MSDN Building Windows 8 clearly states Windows on ARM (WOA) will not support current or legacy Windows applications. "WOA will not support any type of virtualization or emulation approach, and will not enable existing x86/64 applications to be ported or run,” Sinofsky said. “If you need to run existing x86/64 software, then you will be best served with Windows 8 on x86/64."
In plain English, when you buy WOA devices, the OS will be built-in by the hardware manufacturers similar to Apple iPad, Android Tablet, etc.. The devices will come bundled with a number of apps carrying familiar names and looks, however these will be version rewritten specifically for ARM devices, there will be no emulator to run your existing PC version on apps. Luckily, Microsoft will maintain compatibility across platform, meaning a PowerPoint presentation created on your PC will work on WOA or vice versa. Third party apps will be available on Windows App store.
In the same article, Sinofsky also confirmed that both x86 and ARM versions of Windows 8 will be released at the same time. Note that the Redmond company will make available a consumer preview version of Windows 8 on Feb 29.