With some luck, .NET code runs in Mono, so you don't even need a Windows to run it. So if .NET was really the killer app, BSD and Linux would be applicable, too

With some luck, .NET code runs in Mono, so you don't even need a Windows to run it. So if .NET was really the killer app, BSD and Linux would be applicable, too, and those run fine on many architectures. Thus, I think the real "key benefit" are still the native Windows applications. Also, don't forget that most modern computer games use the graphics card more than the CPU, and ARM will have more trouble to compete more with modern graphics cards than with x86.