WWDC 05 made Leapord seem like an OS which would blow Vista away.
Microsoft only needs to say one thing to shut Apple up: DirectX 10
Let's get this straight again:
Not only has Microsoft created .NET 3.0(Crappy name) which includes the Windows Presentation Foundation along with others but:
They are setting the standard for Graphics cards of the future by forcing them to be compliant to the DirectX10 standard. It's all or nothing with card features so the life of programmers is much easier.
They are introducing GPU accelerated GUIs and tearless drawing with the DWM
They've taken strides to improve their webbrowser (Significant strides, you guys heard they dropped the IE7+ name? Yep they listened to feedback)
They secured the OS with UAC (Which has been dramatically improved btw)
as well as other things such as Bitlocker, Flip3D(Although an Expose' type thing would rock)
I'm sure theres more I'm forgetting to list but the point is they do all this AND keep backward compat (IE7, Office, .NET 3.0, hell WPF is even going to work cross platform)