To make matters worse there is WinRT, the runtime. So although you want to abbreviate Windows RT to WinRT, you can't do that without confusing the conversation

To make matters worse there is WinRT, the runtime. So although you want to abbreviate Windows RT to WinRT, you can't do that without confusing the conversation. "Windows Metro" and "Windows Pro" sounds less confusing to me. Microsoft has been reluctant to call anything Metro (instead wanting to say Metro-like) which makes me think someone else owns the copyright to the Metro name.