The ARM version of Windows 8 (a.k.a. Windows RT) is meant to feature both the Metro and Desktop environments, and in Microsoft's words, it's supposed to "feel just like using Windows 8 on x86/64." But there might be one teeny little difference. According to Mozilla, Windows RT won't support browsers other than IE in Desktop mode:
It’s reported that Windows RT (the name Microsoft has given to Windows running on the ARM processor) will have two environments, a Windows Classic environment and a Metro environment for apps. However, Windows on ARM prohibits any browser except for Internet Explorer from running in the privileged “Windows Classic” environment. In practice, this means that only Internet Explorer will be able to perform many of the advanced computing functions vital to modern browsers in terms of speed, stability, and security to which users have grown accustomed. Given that IE can run in Windows on ARM, there is no technical reason to conclude other browsers can’t do the same.
Mozilla is understandably unhappy about the restriction. It claims Windows RT "restricts user choice, reduces competition and chills innovation," and it adds that the lockdown "may also have antitrust implications." Turns out that the blog post decrying the restriction was written by Mozilla's General Counsel, Harvey Anderson. Ouch.
According to CNet News, it's not just Mozilla that's miffed—Google is, too. Here's the search giant's statement on the subject:
We share the concerns Mozilla has raised regarding the Windows 8 environment restricting user choice and innovation. We've always welcomed innovation in the browser space across all platforms and strongly believe that having great competitors makes us all work harder. In the end, consumers and developers benefit the most from robust competition.
I don't know how much sway Mozilla and Google have over the Windows team's decisions, but I do hope Microsoft lets up. I love the idea of having a full version of Windows running on an ARM devices. I think the experience would be marred by arbitrary restrictions like this one, though.