A distinct lack of backwards compatibility with broken old versions of Windows and a strong forward looking compatibility with web standards and modern character encodings.
unix.
but, that won't happen, so I'll stick with my bsd.
edit:
or linux, or hp-ux, whatever floats your boat.
I want the focus on developers that Ballmer has been yelling about for 20 years but has been completely incapable of implementing.
Care to elaborate on that?
Why do you say they're incapable of that focus? Visual Studio is a great IDE.
Windows 98 UI compatibility. It's my preferred look and feel; I use "Redmond" themes even under X.
For MS to keep whittling away the needless UI complexity and preferences bloat
For the entire product line to be axed, for the good of the world. :)
Virtual desktops is the big one for me. I like being able to categorise my windows eg. one for programming, another for other work, another for leisure and multimedia etc etc.
A UI designed by a sane person, instead of the current soup of ancient dialogs, web-like dialogs and shiny dialogs with oddly sized buttons in random places.
Fully POSIX compliant shell.
The same percentage of improvement as there was from vista to 7