not sure from these threads how much WinRT can be used to code desktop apps. Can a desktop app, that looks just like a WPF or Win32 app, be coded using WinRT?

WinRT sounds terrific in terms of bringing XAML to native apps, deployment and siloing the app to avoid viruses.

If you can use WinRT to code a desktop app, would that app be able to run on Windows 7?  Where WinRT is installed on the Win7 PC just like .NET is installed on a PC to run a .NET app.