1. App compatibility - The major issue for any Windows release is that App developed for one OS is for the most part needs to be re-compiled with changes suited to the new OS. How can this be minimized?
Note: Current Win7 version is still 6.1 to support multiple apps...
2. Restarting machine for security updates - Ther has seen tremendous improvements from the past, however further minimizing reboot requirements for every patch will be a welcome improvement.
3. App virtualization - Simplifying app virtualization on Windows will give customers running app in different environments a peace of mind.
4. IE security holes - ActiveX usage for accessing Windows native code from IE posses potential risk areas, which needs to be fixed asap...If not Google will do it in it's efforts towards Google native APIs on Chrome.
5. UAC - User Access Control - How does a normal user know when to say "Yes" or "No" to install a software or not? Why not Windows decide on the fly with some sort of hashing to determine if the software to be run is a malware or genuine one?
Note: There was some sort of Windows tracker, similar to Apple's App store that channelizes all the installations and updates, not sure of the status though!